BB signing in and out: am I in trouble???

I have a Bulletin Board signing in-signing out question.

For the first time, I accessed Allnurses from ...lets just say another location than home. I forgot to sign out when I left that computer. Does that mean someone else can pull up the visited sites list on that computer, see allnurses there, access the site and be automatically signed in as me? (If they do and now see this message I'm busted )

Now that I'm home, I was automatically signed in when I accessed allnurses. Would that happen with every computer I used to reach this BB if I signed in?

If that is so, there could be a LOT of other nurses posting under my BB name in the future. Hope they have a good sense of humor.