Its been awhile since I had Salt in the water. From what I can remember they are really touchy to water chem., no ammonia, no nitrIte, the such. How old is your tank?
If they are not happy w/ were they are at, to much current, not enough current they will move. Maybe that is what is going on, or could still be getting used to your tanks chem.
I would probably test the water to see where you are on ammonia etc.
I hope this helps.