Yeah I've heard (and once again despite my NASCAR involvement I have precious little mechanical knowledge so I'm relying on teh intraweb advice of others) that doing a full transmission flush loosens up all the stuff that's settled into the system and can cause big problems - all you want to do (or have done) is a fluid change - that'll freshen the "flowing" fluid without angrying up the big chunks o' stuff that wreak havoc :-O
My transmission tech told me (a week too late I might add...) that exact thing Cliff. Once transmission fluid runs the cycle of getting hot and cooling down a couple hundred thousand times, it begins to lacquer up, then this unholy flush breaks down the deposits of lacquer, and those little chunks of goo stick in the springs of the ball valves (like adding a spring rubber.) that change pressures in your transmission that control the fluid flow that shifts gears. Changing the fluid and filter is the only maintenance advised for an automatic transmission. Who'd of thunk...?