Customer double-billed when he changed payment term

I have a customer who was paying monthly ($15), and then changed his account to yearly ($150). He was billed $15 on Nov 23, then $15 on Dec 23 and $150 on Dec 23. The Pro Site log shows the following on Nov 29th:

- User modifying subscription via PayPal Express: New subscription created (XXXXXXX: $150.00 USD every 12 months), first payment will be made on December 23, 2011 - XXXXXXXX
- Reminder to cancel previous PayPal Express/Pro subscription sent to XXXXXXXX
- User modifying subscription via PayPal Express: PayPal returned an error: The token is invalid
- User modifying subscription via PayPal Express: PayPal returned an error: The token is invalid

So either Pro Sites requires that a user MANUALLY cancel their subscription (which would seem like a major problem with the plugin), or there was an issue cancelling the subscription. PayPal is configured correctly, though, because everyone else is getting billed normally.

Now his Pro Sites account says:

Pro Site priviledges will expire on: December 24, 2012
Payment Gateway: PayPal Express/Pro
Payment Term: 1 Month
Last Payment Amount: $15.00
Next Payment Date: December 23, 2012

(Note that there's a typo there: "priviledges" should be "privileges")

I've refunded the $15 and the subscription was cancelled when he filed a dispute, but I'm not sure a) what happened or b) if I need to fix anything with his account. It looks like the expiration date is correct, but the term and amount are not. When I click the PayPal Profile ID link, it takes me to the correct subscription. I don't want to mess with the database until I'm sure I won't break anything else. My inclination is to update the term field to 12 and the amount field to 150.00, but that's only a fix for this particular situation. I need to figure out what happened in the first place…

Thanks!