I was listening very intently to MB's points on this also. I know that I am horribly guilty of slapping the trigger, it was something that Kyle hammered me for at Gunsite. I must say that I felt a little vindicated, since a) I knew I couldn't fire near as fast as I was required to if I was feeling for reset, and b) honestly it is a bad habit that I picked up early and have just made it work for me.
As a side note, it is something that I have been working on, and don't do it nearly as bad as I used to. (Penny Drills)