This happened to me back in early December on my 2015 V40 D2 SE Lux Nav. I had been working away and my wife messaged me to say that the car alarm had gone off during the night. When I next entered the car, the mirror glass was in the footwell. That particular night had been very cold and I wondered if that had caused the thin double sided tape to fail. As the car was still under warranty, the dealer replaced the mirror head.