I had that happen to me on a social club ride. We stopped for lunch and I could not for the life of me get my shoe off the pedal. Thankfully, I didn't fall but I did have to take my shoe off and roll it into the bike shop next door. They pried my shoe off the pedal, replaced the cleat, and gave it some locktite free of charge for me. You've just reminded me I need to check my cleats again.