Do the sps look good otherwise?? Eric Borneman says that polyp extension is not an indication that sps corals are unhealthy or healthy for that matter. In the wild sps don't extend polyps during the day due to predation. When they extend at night it's for feeding purposes.

Have you checked your sps with lights out?? They may just be doing what comes naturally. If the corals look healthy then I wouldn't worry, but if other things look off like color changes from good to bad then something may be going on.