FB app runs well for the most part, but I've encountered this issue before. Try force closing the app and run it again - that usually fixes it. If that doesn't work, give the phone a reboot.
Very buggy it seems. Crashes at least once when trying to open it. Tapping on the line to wish someone a happy birthday is very difficult. I find myself tapping repeatedly very quickly to get it to bring up the keyboard. Whole app seems quite slow and I have yet to locate the "Most Recent" change for the News Feed. Hoping for an update...