Have you tried closing the app completely and then relaunching it? From the home screen do the four finger swipe up or double press the home button to reveal your multi task bar. These are all the apps that you have opened at one time. Long press the app until it jiggles and a red minus sign will appear above it. Press the minus sign, this will close the app, not delete it, now press the home button to return to your screen. It's also a good idea to close all these apps, as it helps the iPad run smoothly.
It could also be the FB App being a little buggy after the recent update, dropping an email to the developers would be a good idea here.