buttonbuckmaster

I have a hard time believing that it is the shooter. It happens when either one of us shoot it. Dad has been shooting bows for 30 plus years, 17 years for me. We are not new at this. I have never seen a bow do this before. It not fatigue. Happens on the second round of shooting. Draw weight is 60 lbs, 80% let off. Pretty easy to draw and hold.....Seriously, any ideas before I take it back to the proshop?