My take is, when it's covered under warranty, the dealers tend to swap transmissions rather than repair them. So it might have been something relatively simple, such as a problem with control of the lock up torque converter. They probably could have repaired it, but by swapping it out with a factory re-man unit that's been tested, they have higher confidence in the repair.I had a 2012 impala before with the same setup and never experienced a problem with it. I went to the dealer yesterday and bought a 2015 with 54,000 miles on it. I was on my way home and noticed a shuddering when going up hills and a slight hesitation in changing gears. The car is back at the dealer now and they are apparently replacing the transmission. Is this common, or did I just buy a lemon?