i just had my car, which i got used, in for some warranty work (replace failed ignition coil and wheel-bearing) at the dealer. i think they reflashed the engine and electronics management, because my car is behaving differently. the transmission is buttery smooth, but less aggressive; the ride is also ridiculously smooth and compliant but has lost some 'feel'. idk if a wheel bearing fails all at once or if its over time. i think the slight vibration that i felt before ('feel'), that gradually became worse along with tire roar, was the bearing going bad.
so all thats to say, if you think the transmission is behaving badly; you probably should take it in and have the dealer do a diagnostic and possible reflash. if the car is still under warranty, it should be no charge to you...