Nope, just tested it. I know the Hotbox stays high on the list, so I clicked into adult socializing and viewed it (but not the thread), then tried clicking "show unread posts" and it still showed the Hotbox.
Then I tried logging out and logging back in, then hitting unread posts, and the Hotbox still showed up. So it's possibly completely random.
Do bear in mind that you have a short time after you submit a post to edit it without it saying you edited it, too.