Vanishing Firewire drive - anyone know what happened?

The power went out for a moment earlier today, and when it went back on (and I rebooted) my external firewire drive did not mount.

I turned everything off, waited a couple of hours - same thing. I repaired permissions - nothing. Finally, I moved the input into the other firewire port, and the drive mounted and everything works again.

Anyone have any idea what happened here? I'd like to think the machine just got confused somehow and wouldn't mount rather than something nasty happening to the firewire port. Thanks 🙂