What ruined my evening?

20droger wrote in post #6125553
However, continuous shutter activation is one common form of shutter failure (happened to our 20D). So what happened could also be a symptom of upcoming shutter failure. Since you are still under warranty AND close to Canon, I would recommend sending it in to be checked. At the very least, they'll give it a good cleaning, which never hurts.

Thanks!

The camera is currently at Canon, getting a 7-8 business day cleaning, which would usually take less than an hour.

I had this happen on my 5D about a month ago but I figured out the cause after a while. For me it was my battery grip, the shutter button was activated (not locked off) and I was hiking along the Colorado Rockies camera around my neck and help against my body as I was manuevering through some brush when it started clicking off pictures (I'm always in burst mode). I immediately looked at my regular shutter button and it was not being pressed. So I ended up turning off the camera and then back on, it started shooting again. Turned it off and on again, all was ok the rest of the hike. It wasn't until I got back to where I was staying that I figured that I must have been pressing the shutter on the battery grip... which I keep turned off when I'm out doing landscapes, but it must have gotten bumped.