No, I don't have a clue.....mine sometimes appears like this also.....I then just close the app and then relaunch it. This will usually fix it.
If not try a reset of your iPad.......Hold the power off button and the home button simultaneously, keep holding them in and you may see the power off slide appear and disappear, wait until you see the Apple logo appear before releasing the buttons. It will take a little longer for your iPad to start.