Is someone tampering with my mirrors?
 

I have two Volvos - s60 2007 model and the s70 2009 model. Each has had a side-view mirror (when I say mirror, I mean the glass and the glass housing) pop out. The first time it was the driver's side of the s60. The mirror looked fine until I began to back out and it fell out and shattered. The second time it was the s70 on the passenger's side. The mirror looked fine, but as I backed out I noticed that it was hanging precariously. I was able to pop it back in. Is this a known issue? I suspected tampering because I have been having trouble with a neighbor but she is not sophisticated or intelligent enough to do this sort of thing so I also have doubts. Is the mirror popping out a known issue among Volvos? Thank you in advance.