Wow the exact same thing happened to me last spring on a Trek 620 that I just acquired. I hadn't done anything to it yet but wanted to try it out and was about 15 miles from home. I turned a slow corner and had to stand on it for a hill and the next thing I knew I was on my back holding the bike up. I was fortunate with no injuries or damage other than feeling like an idiot.

Thanks for bringing it up and I hope you heal quickly.