Thanks for all the tips, guys.
Unfortunately, none of your suggestions seem to be the problem.

1. I know for certain that I didn't touch the bulb.
2. There's no apparent moisture problem.
3. I pretty much only run them at night.
4. Still checking for loose & shakey connections, though.
Well, I guess I'll just wait and see how long THIS one lasts... :rolleyes:
Again, thank you.