Swelled up Goniopora

[sneakers714]

I just purchased a green goniopora over the weekend and it has been doing fine. The other morning I turned on the lights for my tank and after about a half an hour I noticed that my goniopora was swelled up. Why is this? Half of the coral had the tentacles extended and the part that was swelled up had the tentacles extended as well. It just looked kinda scary. Is something wrong with my new coral? Please help