Just wanted to thank those who chimed in. I lived with a wobbly mirror for years. Took 2 seconds to fix. This is the equivalent of the old: my computer is acting funny, any help? Sure, did you try restarting it? Oh, no ... yep, it works great after the power cycle.
I'm a pretty hands-on guy mechanically (no so much on engines, carbs, etc.), so it's really embarrassing that I never thought to examine the passenger side of the mirror.