i'm sort of glad i sopld my eggbeaters when they were still pretty much new...
It sounds very much like the nut that holds the bearing and thus the pedal body on the spinldle worked itself loose, and then, when the pedal slipped off, it fell out. If I had 'beaters, I'd tighten the ****er down right now and check it if there's any hint of play in the pedal.