Well, the way the system works is, when paypal receives a payment, they send all the data to us, when we get the data, we send the exact data back to make sure we got it all correctly, if we didn't it's flagged for manual overview.
This prevents people abusing the system and tricking our website into thinking you paid when you didn't. However, no system is without a few false positives. I'm sure your payment was legitimate, however, due to policy, we need to make sure your payment was received.
In a nutshell, we have your payment data, we just need to make sure we got the money and it isn't just lost somewhere in cyberspace, right?
Hopefully we'll have the matter fixed by tonight, however I can't tell the future so it may take up to a day before we solve the problem.