Confirm Delete dialogue box gone!?

Okay -
 
So it's something that usually i'd turn off on a system, but i really like the 'confirm delete of these x tracks' dialogue box....
 
opening a new project right now - and deleting tracks, for some reason, the confirmation dialogue box is not coming up.  i can't remember if there was check-box for 'don't show this again' or not, but there must be a way to get it back.
 
any suggestions out there would be hugely appreciated!
 
thanks!
 
Greg