Thanks for the tips, Tony. I managed to figure out with about 97% certainty what's going on while I was squatting this morning (it's my shoulders, doing something they hadn't done to me in quite a while, and have traditionally been a bit more blatant about it, mostly because they usually get like this from doing power cleans, which have a rather abrupt affect), before having gotten to my computer to check your post, but I went through the movements anyway to see if anything stood out. One thing stood out -- it feels nice to do all of the above without any weight in my hands.