I can't find a pattern yet but my application switcher seems to pop up all by itself. My search doesn't seem to indicate anyone else has experienced this strange behavior. What could cause this?
After your post I realized that pressing the side button was activating the switcher. I know that I had disabled the secondary buttons but perhaps resetting the Pram (I didn't think that the switcher was default, however) or a recent "Time Machine" restore changed the setting. I will disable them again. Thanks!