I've noticed that when I've driven, park the car in the garage, turn off the engine, trans in park, a loud popping sound coming from the transmission (?) It sounds as if the car is clicking, popping into gear, although it's in Park. The garage is level and the car is not being moved in any kind of way. I sometimes sit in the car to finish a song or a phone call and I noticed this yesterday. Searched around but didn't find anyone else addressing this issue.