Password prompt on IOS with Automatic Downloads

I've had Automatic Downloads enabled on my iPhone and iPad every since the feature was released. It's worked great for months. However, for some reason, now every time I make a purchase on the iTunes store on my Mac or PC, I'll get a prompt for my password as soon as I unlock my iPhone/iPad. The new purchase will then download. It's really annoying! Hope someone out there knows how to fix.