I've had this nice piece of GSP for almost a month and it's been waving in the current constantly while the lights are on until two days ago. I've checked my ammonia and nitrate levels several times and they are always 0 ppm for both. I have done two partial water changes in the last two days thinking some new reef mix might do the trick but no go. I have moved the coral to another location closer to a power head hoping for a change, nothing.

Does soft polyp coral do this at times or is there something else I'm missing. The other polyp coral rock I have is open and expanding. I do feed these corals a liquid coral food called "Fuel" which is what was recommended by Big Als once every week.
The only thing I noticed before this coral closed up was one evening my skunk cleaner shrimp was picking through the coral and found what looked like a small ball of something he spent a few minutes rotating around his claws until it disappeared into him. He was going back to that coral a few times every hour to scavenge through it for the next day but I didn't see him eat anything again. During this time the green star polyps remained out and open.
My salinity is stable at 1.026 in this set-up. I'm open for suggestions. Thanks.