Same thing happened to me and I just got off the phone with Apple support - they are saying that this has happened to a lot of customers and since it is a "developing story" they can not provide a lot of details. They did say however that if you made it to the checkout process your ticket was in fact reserved and once they get things sorted out they will e-mail you at your Apple ID to allow you to actually purchase your ticket.

I had a ticket in my cart and then got an error when I tried to actually buy it. I hope you're right!