Hard to say what caused it but we had a deer we named Cactus b/c his antlers were formed just like your buck's. His antlers hadn't evened out but he gained a ton of mass between yrs 3 and 4. When shot he scored 148" with 8 1/2" of mass atthe deformed antler's base. Awesome deer and we only have one other deer with a deformity and that is a drop tine spike buck nothing like cactus. I don't think it would hurt to wait and hold out since this is your first year hunting there unless he is the biggest buck and you really want him.