As has been mentioned by everyone -- it happens to even the most experienced riders. A few weeks ago, I got off my bike during a ride but didn't realize I got mud on my cleat. When Texas mud dries, it's as hard as concrete. Anyway, by the time I got home, the mud had hardened. I rode up to my garage door and tried to unclip, but couldn't, and there was no place to go but into the garage door then down. The good thing, however -- the fall broke my cleat loose.