Star Polyp Mat Lifting from Rock? Why?

I just noticed that the purple mat from the star polyps is starting to lift from the rocks! I have no idea what is causing this. My water parameters are all perfect. I have good flow. The only thing that isn't very good in the tank is the lighting, but I placed them close to the top so they are closest to the light as possible. The polyps themselves are good. They fully open in the morning within a few minutes, are a light pink color and the very tips of them are starting to turn green after I placed them up closer to the light. The tenticles on some are starting to grow longer, so they like where they are righ now. Why is the mat lifting from the rock? It wasn't like that when I got the polyps about a week ago.

 

It sounds to me like they are spreading/growing. My mat was bigger then I rock I got them on two weeks ago. I placed that rock on top of another rock, and the mat is now starting to get bigger.

That pic is about a week after I got my GSP. Now it is even bigger and looking healthier.

 

Post a pic if you can. There may be something underneath in the rocks causing them to come loose.

 

A pic if possible, cause my gsp are growing offshoots. The outter edges will be white where growing. Then turn purple.

 

That is good, you can remove it now!