[InvisiBill]

Hmmmmm. My first theory was that he ended up at the "you're not logged in" page while being logged in due to a bad link. Sometimes you can go directly to e.g. /YouHaveBeenLoggedOut.php while logged in, and it will say "Thanks for logging out", even though you didn't actually log out, because you went to YouHaveBeenLoggedOut.php directly rather than going to logout.php (which logs you out then redirects you to YouHaveBeenLoggedOut.php afterward). But it looks like vB doesn't work that way, so it isn't really possible to do that.

My next guess is along the lines of what csmith12 said. I wonder if while vB was generating the page, the timing caused it to pull up the main part before the login process finished, but other parts (like the user info) were loaded after the login finished. So half of the page was made while logged out, and half while logged in. I'd expect the parts to be the opposite of that (user info not shown, but logged in thread there), but I haven't poked around vB too much to be familiar with how it actually generates the pages.

Or maybe the NSA's sniffer on Alex's server hiccuped.