underwhirled

I was waxing my car yesterday and the housing for the drivers side mirror can be removed (partially) by simply wiggling it back and forth a bit. After reading all of the posts on how to remove the mirror to access the bulbs, I didn't think this should be possible.

I can't do it with the passenger mirror housing. Is there something I can tighten or should this be a warranty item. It isn't really a big item since it doesn't move when driving or anything, but I'd hate for it to vibrate loose on a long trip so I want it tightened.

Any suggestions other than having the dealer look at it?