I've heard stories of mechanics who joyride cars and do burnouts and who knows what during test drives. When your engine has a lot of power and you see the owner put a lock on the power, it can definitely leave a foul taste in the mechanics mouth, depending on who it is. I don't know for sure if that was the reason, but its likely. The ding was definitely not there before I arrived and was very close to the roof of the car. When they lift the cars its extremely unlikely for someone to have dropped something on it. Even the Paint less Dent Repair guys said that this was definitely a hard and calculated blow.
Also, I noticed it much later since it was in a hard to see spot and I didn't want to go back and start a war with the dealer. Plus the dealers where I live are backed up and most appointments need to be scheduled months ahead.