Over the past couple days, my iPad has been frequently asking for my iTunes password. At first, it was happening almost constantly, but it's toned down...a bit. Usually, it just asks me whenever opening the app store or each time I open a book on iBooks. Obviously, it stops for a few minutes if I enter my password, but that's more of a hassle than hitting cancel--also, since I don't know why it's doing this, I'm leery of entering it. I've tried restarting my iPad, and I have nothing downloading. Anyone else having this problem?