Yes...it's the torque from my grip on the bar (while I'm trying to stay as upright as possible) that aggravates it. I don't have a problem other times of the week when I'm doing rep work with lighter weight.
I didn't think of warming up the bi's and tri's though. I usually do band pull aparts, and internal and external rotations for shoulders. I mostly focus on dynamic stretching and mobility work on my lower body. Next time I'll try some more upper body work in my warm up.
Thanks for the feedback.