overdriving the master?

Of course I'm trying to get the max final volume, but I see the red light (between the "Post" and the "Off/On" buttons) on the Master flashing at me and assume i'm over driving it, even tho it is not peaking on the meter. 
Is this a bad thing and, if so, what do I look for? (It does sound a bit raspy)

That light is not the master channel clipping, it's the master ProChannel overloading. 

First thing to do is get your console open and check to see if any of your track PC lights are turning red as well. If they are, then that overload is going to be reflected in the master PC. Reduce the gain in the track PC that's overloading. 
If you still see overloading in the master PC then either move all of your track faders down until it stops, or like noynekker says, trim the gain using the gain knob at the top of the master PC. 

If by "out of the red" you mean the meters, then I have no problem there. It's the PC light I was referring to.
I have busses for vox, guitars and drums and they are all just starting to glow a light colour just like the various trax.

An important thing to remember is that none of the track's ProChannels can be overloaded by faders as long as their ProChannels are set to "pre" rather than "post" - rather, they overload when the inputs to the ProChannels are too hot. The master bus, however, can have it's ProChannel overloaded by the track faders, since they are summed into the master ProChannel. If that makes sense :)

And yes I am just now "getting" the idea of "Less is More" with the faders. IOW pulling the rest down instead of just boosting the one you want clearer. It's counter intuitive to an old band guy who's traditional way of being heard was to crank it to 11.

Its a balancing act when determining the volume levels for the plugin effects on buses and the send levels of buses for each track......

No it is not. Some of you will know that I have talked about K system levels within your DAW and the use of VU meters. It is very simple, you choose a reference level and work at it. The VU keeps you accurate in terms of the rms levels that are present at any point in your signal chain.

It starts with tracks. With the VU and K system approach you are already tracking every track at the correct and same level. Great. Now insert plugins. Precise levels can be set in and out of any plugins. You will never need to overload any plugin again. (unless you want to and that is fine too if its your bag) 

Busses. Well the same said ref level and VU metering takes place there too. All your busses are now sitting at the exact same rms levels. And still well clear of 0bB FS. No distortion due to any form of clipping is happening on tracks, plugins and busses now. very nice. If a buss is being overloaded, simple. Just group all the tracks going there and pull them down a tad, done.

Masterbuss is a combination of all busses and tracks. Same ref level and VU metering exists on your master now. Whole mix sitting there still down at the ref level well away from 0db FS, not a red clip light in sight. And for those of you who may like to mix into some master two buss compression. No problem use it but just ensure the levels either side of that are still at the K level. (make a note of it in your title and also always print a version without any form of processing in case you ever want it, by using K system you now have two prints at exactly the same level, very nice!) 

Every piece of music is done this way, no difference for any song. 

Mastering is, well, great. You now have a whole bunch of tracks that are all at a perfect and same rms level and still well clear of 0db FS. Now mastering is a very simple job level matching wise because everything is already level matched!

No one can argue with the concepts I have outline above.  Anyone doing anything other that what has been stated here is shooting in the dark, hoping and balancing, not really knowing what your levels are, getting masters of different levels, bringing clip lights on here and there, overloading plugins, and so on. Modern DAW metering does not allow you to this effectively. By simply adding a VU meter plugin and working with a ref level in mind and keeping an eye on it everywhere you can enjoy all the wonders of K system and VU metering approach. It works. It is borrowing the concept from the analog days and bringing it into the digital world.

You mix will sound fabulous because at the end of the day the whole mix is still sitting around the ref rms level the peaks are there and not clipping anywhere so it will just sound fabulous. Just turn this up in your control room so the volume is right. This process does require you to be able to monitor at high volumes if required. Then you get the feel of the final mastered result. If any of you are working in places where you cannot monitor loud then you are pushing it uphill.

The mistake people make is trying to achieve mastering approaches and final mastered levels too soon within the mix process. They end up pushing things way too hard every where in the signal chain. Mastering is a different concept and that is the time to achieve all those desired mastering results.

Many of you have produced great mixes without any K system/VU approach and I am happy that you have done it. It does work but if I measured all your rms levels everywhere with respect to a ref level, they would be all over the place. It is a bit of luck that you did end up with a great result and even though you may have been using some sort of systematic approach to get there, it is still not as good and effective as the K system/VU approach. I am also sure that those of you who are getting great mixes without clipping anywhere are in fact doing a form of K system behind the scenes so to speak. The K system, approach just standardises it all from project to project and also from engineer to engineer. If I get other work that has been tracked/mixed from K system point of view it just a dream to mix or master.