Huh. I have also seen every episode and I can't recall the theme music at all. I know it had an intro because I remember thinking the visuals were cool but I can't bring back a single snippet of the music. Weird.

edit: I had to look it up because it was bothering me. As soon as it started playing I remembered it, I actually think it's a fantastic theme song. It's spare and unsettling, which is perfect for the show but I can kinda feel why it's hard to recall. I'm glad you pointed it out.