What's next, the Easty Bunny??

Today in the van on the way to karate, E and I were discussing when his latest loose tooth might fall out. Then he says "Mommy, are you the tooth fairy and daddy is Santa?". I squeak out "why do you ask that?", and he responds "Well, this 3rd grader said....". I don't really remember the rest of the story, as I was not prepared for the question and was busy trying to figure out it it was time for full disclosure. I believe my explanation contained some discussion of how they are real if you believe in them, some reference to the movie Polar Express and some bell that only true believers can hear, or something like that. It was so lame; I'm sure he noticed. A couple minutes later I ask "so do you really think I'm the tooth fairy??", and he said "uhhh, no". I believe my 5 year old is now pretending to believe just to humor me.