I don't intend this to come across as mean, but every time this is asked it reminds me of the people that call IT departments and say "the computer says my password is wrong, but there's no way I forgot it", as though maybe the computer is mistaken. Usually it's by people in the west who sign in in the evening, which is the next day GMT time, but I'm guessing if you referred to yesterday as Sunday two hours before midnight GMT, you're probably east of the line, so that makes it somewhat more unusual.
A moderator can check the access logs to see if you missed a day or not, but maybe access logs should be accessible by that user, if this keeps coming up? It might be as simple as adding a line to https://stackoverflow.com/reputation to indicate if you visited the site at all that day