Don't worry about it, I did the same thing to a doe at 8 yards yesterday. There was no wind and I drew when she was walking at 10 yards. She had been on alert for 10 minutes so I readied my pin immediately and released the arrow. I missed right over her back. I hadn't missed like that in years. I shot my bow today and it was hitting great all the way out to 30 yards. Sometimes it is user error and not the bow. We all lose sometimes, just get back at it and go for it!