I was at the range with my buddy just last year and we were shooting side by side when all of a sudden I hear crrrrACK!!! Sounded just like a 22 rifle fire. I look over and knew imediately what happened by the look of shame on his face and the fact I never seen an arrow fly down range. Yep , he was busy talking with me and never loaded an arrow.[]
It happens to at least one person every year at our local range.
I'm not saying it's what happened to you but it sure sounds familiar.
If you did have an arrow nocked I'll bet it didn't leave your string with the guidance of your rest.