Interesting... we'll look into it! THanks for posting
I don't think you have to worry that someone else is logging in as you, but if you're concerned you can change your password at any time in your profile options.
Also, have you checked your timestamp settings in your profile at all to make sure they reflect your local tiime zone?
Once you've set your time zone properly log out completely and then log back in - check the 'remember me' box when you do so - and it should be fine.