Rear windows roll down on their own?

[CandE]

Very strange issue here. The rear windows on our 2005 S40 roll down automatically and randomly on their own. It first happened when my wife unlocked the car with the remote key, but now it happens randomly. Anybody ever seen this before or have an idea what it might be? We recently brought it in for the 52500 mile service but as far as I know they didn't touch any electronics.

Thanks
Chris