No explanation when user is auto logged out

Recently I waited too long before posting a message and I was auto-logged out, but the user interface did not make this clear. It just said "unauthorized" or something like that, as I was trying to do something that you had to be logged in to do.

I think that Drupal should have told me, "For security reasons, you were auto-logged out and you will need to reenter your password if you wish to continue" and then I should have been brought back to the page where I could hit "submit" on my new forum topic again.