Yep. It's happened to me, too. No clue how.
Glad to hear it still works, though. I'll be crushed when my six year old Barracuda dies on me, but I don't see that happening in the near future.
I'd recommend getting the HDTune Pro trial and running the disk test and health check on it to be sure nothing's going wrong, though. Just to be safe. You can get the free non-pro version, too, just for monitoring once the trial runs out.