No.... When someone checks remember me, they are still subject to the cookie timeout with respect to the Who's Online. The difference is that if they timed out, and had written a post, it doesn't take them to the login page.
What I find odd is that even if you had been logged out, when you log in, it should have posted it for you...
Another option is to copy/paste your post into notepad before you hit submit as a precautionary tactic
