being you dont have a 100,000 miles on it, no way it got a tune up from a dealer.
hows your fluid look, nice and red? full when hot?
it could be a clogged filter as well, if the tranny never got serviced. 30 to 50 thousand is when you want to do a first service. pan drop and filter. do that every 50,000 miles from then on, and your tanny should be happier. as long as you dont beat the tar out of it, v8's eat these trannys up if abused.