From what I see on the print out, they did it by the numbers and went a little further by checking and replacing the torque converter and sensor. You've got plenty of warranty left so take it easy on the girl for just a bit then drive it like you stole it when it warms up. I've never read anything to really call out the root cause but if I had to guess most break out when shifting into reverse (reverse circuit pressure is generally the highest). Enjoy having your ride back, mines been in self imposed exile due to summer tires so I've been back in the beasty SUV until temps come back up a bit.