any idea of how the problem happened? i dont think its because your right arm is dominate unless you really use it frequently oppose to never using your left? trying to come up with ideas on how it could happen do your work out at home maybe your bench isnt level so it messes up your lifts (happened at my house) hows your form when your benching is the bar straight or is one side higher than the other that could be the problem to me youve probably focused on one are more than the other and thats why its happened