What Chuck Fields said it correct and saves me time. Also, the fact that other people are moving has nothing to do with your game. You are the OP's opponent and you both shoud be concentrating on beating each other. They are not part of your action. Your getting up is like reminding the OP that it is, or shoud be over. You might as well just have blurted out that its over . I have never played in a league as I view pool as an individual competition. I wouldnot shark until it is done to me. However, If you had done that to me, I would have said go ahead and rack, and moved the marker over. I would suspect this might set off a debate that should get under your entire team's shin by the time I escalated it. Getting up because the team caption motioned for you is lame. Remain seated. After the shot, go to the caption and remind him you opponent was still shooting. Btw, you can do anything when I shoot.
Funny, but (oh and I agree with your entire post) I always had a problem with movement while shooting in the league, especially from my teammates checking if balls go by one another while I am down to shoot. It didn't take long after stopping league play and playing tournaments to where nothing bothers me when I am shooting. I think it is being in situations where it isn't such a big deal anymore that gets it out of your head.