Tubby has done that to me in the past too. I don't think it was intentional, I think he just thought your finger was another treat. After all, it probably still smelled like a treat if you were just dishing them out. Tubby never broke skin though, so I can't help you there, but I know cat bites can be serious so watch it closely.

And it's funny, I always make Peanut work for her treats too.