Dam, sounds like it could have played out worse. They can cause you some injury when that happens! Was there any way something went around the can while drawing back? (Between the can and string). I don't think you could tork the bow enough for the string to come off IMO. I had it happen once with my wife's bow, while I was drawing it back something went between the cam and string when it went around it jumped off. I think it was something on my jacket if I remember correctly. I'm not a bow expert, but that's what I have had happen.