And, no, I didn't start at the top of a hill and drive down the hill. This was a short trip from home, to a store and back home. Instead, I think the software is confused.
My blind spot sensors were on when they shouldn't be. So, I took the car in for service. Apparently, the reflective tape that is meant to prevent false positives had come loose due to vibration from snow tires (since removed for summer tires). The dealer ordered tape from GM and installed it 2 days ago. While there, the dealer charged the battery.
At home, I normally use the hilltop reserve feature. But I have it on 100% charge for when the GPS says the car isn't home. So, the dealer likely charged to 100%
When I got home, I parked the car and didn't connect it to the charging station. Friday night, 5.0 mile trip to go out to dinner. We left so quickly that I didn't use the remote to start the "engine" before this trip. After that trip, even though it didn't need it, I connected to the charger.
This morning (Sunday), I went grocery shopping. I used the remote to start the "engine." The charger actually engaged (or so it claimed) but the Entertainment Display said 0.2kWh since last full charge because it was using the A/C.
Nearing home, I noticed 51.1kWh so I thought I'd share my story.
Hopefully this is nothing more than an engineering corner case and it will reset on its own.