I find it normal for them to stay closed for a while after being irritated. Sometimes I pull off a powerhead and just spray down everything and if I spray the GSP's quite a bit they stay closed for a few days. Of course they do end up opening up again all big and wide with no harm done. Sometimes they will open up in small individual clumps within the whole colony, then later all will be open. Its no big deal for me to seem them closed for a while, because I look at it as a way to slow down their crazy growth. Just watch them encrust everything they touch.