I had a GSP colony a while back that would close up if my alk dropped too low. If the alk got below about the 7dKH you listed, then it would stay closed until I brought the levels back up. I'm not sure if it was the alk level itself or the wider pH swings that the lower alk allowed that was really the culprit, but my GSP was like clockwork - if I missed a couple of doses and the alk fell below 7 or 7.5, it wouldn't come out. If yours is simply annoyed from the irritation, as alasg001 suggested, then give it another couple of days. However, if it's not coming out by Saturday or so, you might try bumping your alk up to 8-9 dKH and see if that helps.

FWIW,
Derry