"You’ve activated Google Wallet on a new device" -- Google Wallet compromised?

Had two of these messages today, both times I've logged into the website and disabled all devices.

Called Google, they indicated they'd had a few calls about this, and are escalating things.

I have a Nexus 4 and a Nexus 7 (original).

Frustratingly, I cannot remove the credit cards on file for my Wallet account.