After having been logged in for months on my Mac/Safari, twice within the last two days I've been greeted by the "Welcome to the Q&A for professional and enthusiast programmers" message and had to re-login. I never click the log out button, nor have I cleared my cookies. Have there been recent changes that might explain this? Will it continue?
Update: I remain logged on at work (Win7/IE8), despite having to re-login twice at home.