Can you tell us more about your tank, such as size, water movement, lighting, water quality and water chemistry parameters? Did you change anything in the tank lately? Add new fish, or anything at all?
Gads, I wish my GSPs would close for awhile, or at least stop spreading like wildfire!
While the following video features xenia, there are lots of shots of our GSPs. They get quite a bit of flow and are under rather cr*ppy PC lighting....
http://www.lostmymarblz.com/v-120g-xenia-fe-06.wmv