As my season is winding down, (this is my last weekend working, and it's a double header :S) I'm starting to notice dust on my sensors. I've been shooting with my 20D for a couple years now, and I've never really gotten a good cleaning out of it. My pretty new 30D is doing OK I think, so I'm not so worried about. Anyway, my question is, should I just send it to Canon and get them to do a check up and tune up? Is there even such a thing? I haven't had any trouble with any of my equipment, but it's better safe than sorry right?

The night before each shoot, I use my rocket blower and blow off the sensor while holding the camera lens side down.
