I think it's a cache problem again. Something like this happened temporarily a little while back and I'm pretty sure they said it had something to do with that. I noticed this morning that when I go to the "Home" page/tab it shows me as logged out, but if I click on a specific section or thread it shows me logged in correctly. You might want to PM a mod if it happens again, but it's probably just a temporary thing from them updating or something.