Hi Otto,
I been having the same issue with auto posting, it seems that it works great at first, but then the connection expire. Though the admin panel shows that the User ID token, the app Token and the Fan page token been found, it will only auto post after I press the grant permission button again, I been trying to debug it for a few days and noticed that it usually expire after around 45 min from the time I pressed the grant permission button, once I pressed it again it will work for another 45 min.
I assume that you are right when you are saying not to log out of facebook since it breaks the access token, what would be the best way to do that via wordpress, or do you mean just not to log out of facebook (I am always logged in)
Thanks for a really great plugin and your effort on this!