TSB was done yesterday along with some others. Tech at dealership didn't know why it happened either. He just suggested keep turning the key off on off on off on lots of times. He said it was typically more of a problem with the push button start.
Apparently with one of the updates, he said, the battery will not be charged at all if the voltage drops below 11.6V. That hasn't been a problem. Just the same, I picked up a cheap load tester for occasional use -- car, boat, truck, etc.