I'm guessing an electronic gremlin
I've had only one incident but mine was the tranny would not shift from auto to the paddels while trying it on the freeway so when I got off the freeway and stopped at the light it still didn't want to got into manual mode so I pulled over and shut it off and restarted it and the problem went away and has never returned. But keep us posted if it returns and maybe just try restarting it if it does.