vCPU is not factored into the billing anymore and hasnt been since Jan 2011. Only vRAM is used for vCloud Bundles. vCPU is provided as information only to help characterize the virtual machine in the detail billing and detailed usage reports. The intension is to eventually provide more details on vCPU usage, storage, network, etc for those who wish to pull that information from the Usage Meter for their own billing purposes and not for VSPP.
I'm interested to see why this is happening and we'll take at look to see if we can replicate your error. Thanks.