It's just a test to see if you are still compliant.Judgement Day. I think your Volt just became self aware.
I had something plugged into the OBD port and it freaked out. Said the same thing.I get a message about once a month or so that my rear view camera needs service. I just ignore it, and it keeps working. That's life with COTS grade sensors.
My Jettas did that.I had another car where that action was required to calibrate the auto-close and auto-open window function. That memory would sometimes clear if you disconnected the battery, and those auto functions did not work until calibrated.