Your login has expired please re-login to the facebook app (2102)
Then when i log back in it says the same. Sometimes it works for 2-3 min
then that comes back up.
I'm an Ex-facebooker. I left because they never seemed to have enough servers to accommodate the millions of users, and just couldn't keep up.
Having said that, have you checked FB via computer to see if there is a similar problem? Of course, it may be their ability or lack there of to maintain mobile connections.
Something was up. I logged out and back in again to test for ya. On login I got the welcome message in my FB inbox. This usually happens after they have tweaked the servers probably due to the FB refresh a few days back.