I remember a similar incident riding on the last car of an R38 train (this was towards the end of their lives, around 2007-08). We were plodding along on the express run between 168 and 145, probably passing under 155, when one single door slowly drifted about halfway open on the left side of the car. No loss of the indication light, no loss of power, nothing. About 5-10 seconds later it engaged the door motor and closed. Luckily the car was almost empty and no one was even standing up, let alone leaning on the doors.