Noise at beginning of exported audio MP3s

Hi,
 
When I finish a song and want to render it down to an MP3, about a third of the time I hear a little quick noise at the very beginning of the finished track. Maybe I'm doing something wrong?
 
Here's my method:
 
1. Finish song
2. Highlight all the tracks
3. Hit File>Export>Audio
4. This opens a new folder window where I select "MP3"
5. I name the song, add artist name, etc.
6. There are lots of buttons on this screen and I leave them all checked, such as enable fast bounce, etc
7. Click "Export" and it renders the file
8. Play it back and 2/3 of the time it sounds fine but about 1 out of 3 there is a very loud little noise at the very beginning that lasts only a nano-second but it is definitely there.
 
My dithering is set to triangular, rate is 41,000, 16 bit
I use an Apollo Twin Quad with Thunderbolt 3.
 
Should I change anything?
 

My first thought was the same as Geoff's - you may be hearing some leftover data from a previous playback. One way to be certain to avoid that is to do your export after opening the project, without playing it first (after waiting long enough to make sure any sample libraries get loaded, of course). Or, you can simply initiate playback for a second or two, or however much silence you have at the beginning of your song. Stop playback before it gets to the actual data. That'll flush any lingering reverb tails.

I kinda do master it with Ozone 8. Everything is funneled to it. And yes, I think it's some sort of reverb tale or similar. 
 
More info:
 
I typically send all vocals to one sub that has Waves vocal-rider, another sub has all instruments (with send to vocal-rider), another sub for reverb and another for delay, all of these are directed to the Master sub where I have Ozone 8 Advanced. Sometimes I'll add another sub for Anteras Harmony engine.

Bitflipper is correct, and all you have to do is edit the wav that you created via the bounce. It's happened to me since Home Studio 2004.

Hi. I've had this happen when a sound hadn't released properly. In those cases, I press play a second and stop again.
That usually cures it for me. It doesn't happen on a regular basis, so I haven't gotten to the cause of the problem.
All the best.

Delays can be noisy too.  Very noisy!  I always export to WAV and if I want to make it an MP3 I'll use Audacity later but certain types of delays or flangers create  a "breathing" sound even in the point between any silence you have at the beginning of the project until the music starts to play.  As Bitflipper says, it's best to do an export from a fresh and non played launch.  I also find it a good idea to keep at least three measures empty before starting the music.  This gives the reverb/delay tail time to dissipate before the music starts.
 
John B.