Notices about accessing store from a new device

I tried to make a song purchase tonight and received an error message that said I was accessing the store from a new device (not true), and I was asked to provide more billing info before my purchase went through. After the purchase, I received an email that said, you have just made a purchase "...from the iTunes Store on a computer or device that had not previously been associated with that Apple ID." Again, that is not true. I'm using the same computer, same account, and live in the same home with the same ISP I've had for years. Why the false notices?