Back to the original question, check that there are no marks on the cabin roof just under the rotor mast fairing. These would indicate that there has been mast-bumping.
This also happens if the aircraft falls off its ground handling wheel on one side, like mine did when a friend let go of the wheel handle half way round. The sideways whip in the mast made the fairing hit the roof and crinkled the side of the fairing.