My car was rearended in a parking lot while parked and unocupped. It's a Chev Lumina with automatic trans. I clearly had the car in park when I left it. Came out and an old lady hit my car from behind (she was ok thank God). Anyway, she hit it, not very hard, and it rolled forward about 30 feet into a curb. Mininal damage to my car. Needs a new rear bumper. But what about the trans? How in the world could this have happened while in park? The car runs perfect right now. Reverse is good, 1/2 and drive are good. Overdrive is good. What gives? Should I be concerend that something transmission-wise was damaged?