It's been known to happen. We actually get something a little worse, something they call an "ancient landslide." If you are not lucky, your house might be built atop one.
When I first moved here there was a nine million dollar home that got a little crack in the driveway, that eventually expanded to be about a foot wide and they had to knock it down. The guy that bought only lived in it a few months before it went sliding down the hill. Here's a blog about a more recent one:
http://wncsos.blogspot.com/2008/02/land ... thern.html
I live in a cheaper neighborhood where the ground is more stable - plus I have a jungle growing on the slope behind my house and the roots help hold the dirt in place.