EXTRA INFO: I use google OpenID to sign in. Maybe that's the cause?
UPDATE2: and again today (17 Oct 2010).
UPDATE: just happened again (10 Oct 2010), both on SO and here. check out the FAQ!
Maybe there's been yet another rollout? But even if that's what's happened, why log people out?
When I don't visit SO for a few days — not sure exactly how long the time is — and come back, I need to log in again. EDIT NB: if I visit daily, I don't get logged out.
This seems unnecessary, and so the ten seconds I spend waiting for the log in screen, the time spent actually logging in and then the ten seconds I spend waiting to be returned to the site are irritating.
I don't think there is any advantage to SO in logging me out. (Is there any?) In fact, because it is so annoying, I think it discourages use, especially to those at the margin, where growth occurs... it is actually actively hostile to intermittent users. Reddit and HN let me stay logged in indefinitely, and there don't seem to be any problems.
Therefore, this is a feature request: please extend the login time to be indefinite (or at least provide an option for that — is there one already? I couldn't find it).
Or: please stop hassling me and let me participate! :-)
EDIT others have the same problem http://news.ycombinator.com/item?id=1700682 Note that if you are a regular user (eg visit daily), you probably won't experience this yourself. And that's probably why it hasn't been noticed, why it isn't fixed - and why it isn't quite believed. ;-)
EDIT seems to be a bug, so I'll add details: I'm using FireFox 2. It's an old browser, but I don't have this problem on any other site (eg. reddit, HN, gmail).