Sounds to me like there is a disconnect somewhere between you and Google. Did you change any code that implements checkout? Or did they release any updates lately? Have you tried posting on Android dev forums?
Yes, it does sound that way, but unfortunately I'm very sure its not. I don't do any of the handling of transactions on the Market. That's all done by Google. All I do is post the app to the Google servers and they take care of the rest including listing it in the store, processing payments, etc. Additionally, I did post in the Merchant Forums but have yet to get a response of any kind. Thanks for the suggestion though! :-)