badOHtenTAHOE

just noticed this yesterday. i was driving down the parkway cruise control set for 68mph and wile going up a grade the transmission would downshift to maintain speed up the grade which is normal, but right around 2500 rpm when it was at the peak of that gear ready to shift to the next highest gear, it shifted up then down very fast and back up within a split second. it did that a few times during the 90 mile trip with cruise control on and off also. today driving locally it happened once. its only once in a wile cause i even tried to make it happen again and it wouldn't do that. seems like its only when i don't really have my foot to heavy into it. im thinking that my TCM or PCM might need a reprogram, not sure if there's a tsb but im going to the dealer in a couple months for my 30k service(which does not include a transmission service) so im going to have them check it out unless it gets worse. hate taking the truck to the dealer because they always get greasy hand prints all over everything. any input?? thanks