hmmm...sounds to me like someone wasn't keeping a close enough eye on the eggnog!
Cats are, by nature, psycho I think. Don't get me wrong, I love 'em and have two of the best kitties in the world, but I think sometimes all that pent-up natural prey drive that doesn't typically get nurtured in house cats just has to unleash itself every so often and your poor hand was unfortunate victim.
Clean it often and well. I knew an animal control officer that almost lost her finger and was out of work for over a month because of cat scratch fever. (That was from a feral cat, though - don't want to alarm you. I'm sure you'll be fine).