It probably has a crack in it so that the jaws don' t hold the string. If you' re using a release it can also push the arrow off the rest on let down. With a Muzzy zero effect rest and a string loop these things don' t happen.[:-] Ok.. they could with a bad nock. I know it' s frustrating as all get out, but think on the bright side. If you had released it and it has a crack it could have exploded and hurt you or sent the arrow off in some wild a$$ direction or wounded the deer. Dragging this equipment through the brambles day after day, hauling it up and down from trees and things can take it' s toll. I' m particularly tough on fiber optic pins in cold weather. Now there' s a bummer. I drew back on a buck in NY a couple years ago, went to put my 20 yard pin on him and it was gone. I just centered the hole that was suppose to hold the fiber optic thread and drilled him, but it was a nervous moment.