There's nothing wrong with the horse, he just spooked once and started bucking and he won, no big deal he's over it he was over it after the whole thing happened your the one that need to let go. He gets antsy because you got antsy first, you can take the brokest horse in the world and if you are scared the horse will be too. Horses can feel you tighten up. Have someone else ride him for you to show you that there is no big deal. Just don't think about it, everybody falls off once in a wile it's not if it's when it's going to happen and how bad, I am due for a good fall right about now LOL. Take it easy.