I had one nibble a fin when I was drift diving on a wreck off of Palm Beach once...it was a freighter that a U-Boat nailed right on the edge of the Gulf Stream, and the current was a *****. Damned shark stayed right with me, and just kept nibbling at my fin. Worst dive ever.
Wow, that must have been nerve-wracking. You are incredibly lucky that he taste-tested the hard plastic fin and not your leg.