The problem persists. Other similar symptoms occur, which are all fixed by refreshing the page, such as a thread subject line not showing that I've posted a reply when I go back to the board.
I'm disappointed at the lack of a technical reply. I can't imagine I'm the only one experiencing this sudden blip.
The function has always been browser dependent--it never worked that way in Firefox that we're aware of, while it did in IE for awhile, then we changed something, then we changed it back. So whether or not that flag will clear when you return to the page will depend on whether your browser is reloading the page or not.