I eventually just kind of figured it out. There was possibly also an incident where a present still had a price tag on it. That and Santa's writing looked suspiciously like my mother's, as does his wrapping paper choice look like the shit that my cousin's presents from my family were wrapped in. She still insists that she wraps the presents and writes the tags for him so he has less work to do. Thanks mom. A for effort, but I'm 23 and it's okay to give it up. Really. I won't be mad.
That being said, is the Santa story necessary when you raise a kid? I've been considering parenting stuff lately (not teh_preg0rz or anything, but just been going through some methods and ideas and how not to fuck it up), and I've been wondering if stuff that like is essential in raising a balanced kid with a good imagination. If I find out it's not, I'm really not sure I'll bother.
**Edit**
Heh... there's one Christmas morning that my parents have on film... Santa left me a note, I think regarding why he didn't drink all the milk, and I remember it bring printed on a piece of printer paper (the kind that came in a looong strip with the holes down the sides), and I remember that being in her writing. You can see it on the film, too. That may have also contributed to my realization. Not sure if there was ever one specific moment, really.