Mine is very active as well. Always on the move and grazing for pods and whatever other kinda critters it can put in its mouth. It might not be used to you also. My tangs used to do that at first whenever I would approach the tank, until they got used to me. Now they all come out whenever I go near the tank thinking they are going to get fed. But as the other person said, if its breathing rapid or rubbing on rocks, not eating or anything else not normal, try to get it out and put in a QT. Just keep an eye on it. They are fairly hardy and sometimes takes them a bit to get used to their new home.
Hope it gets better. They are really cool fish.