My interpretation of that is that during rest, there is not enough circulation to the arms.

I just finished reading "It's Not Carpal Tunnel Syndrome" and they identify chronic muscle tension as a problem that can reduce circulation and cause the kind of pain you are describing. I would say hypertrophy could do the same thing as well.

Can you at least reduce your rehab exercises? Maybe cut the reps in half and the weight in half?

Also, I catch myself tensing my shoulders way too much either in response to minor amounts of stress, or poor sitting posture. I have to monitor myself constantly. I hope someday, relaxation and good posture become my norm, but for now I have to recheck myself throughout the day.

Good luck.