Me too. iTunes just shut off on me about five times today. I went to an Apple Store, and it happened there, too. The girl at the Apple Store didn't have an explanation. They were real busy, and she told me if it continues , to make an appointment and go back.
Try signing out of your account and restart your iPad.
Go to Settings>Store>Apple ID and tap the ID and sign out. Restart the iPad by holding down on the sleep button until the red slider appears and then slide to shut off. To power up hold the sleep button until the Apple logo appears and let go of the button. Go back to Settings>Store> Apple ID and sign in again.