It happened to me again today. I rode down a mile long expressway with the throttle off and came to a stop at a traffic signal at the bottom of the street. I was in Sport mode at the time. I had to wait for about a minute for the cross traffic to clear (I had the right turn signal on as I was making a right turn at the intersection) and the bike failed to start up again when the throttle was turned. I turned the key off and back on and was able to immediately take off, after the computer rebooted. I rode around for about another 30 miles today, stopping at longer lights and never had another problem.
Right now I am not seeing much of a pattern, other than coming to a stop and waiting for for a short time. I really hate random and intermittent problems. At least it isn't happening while the bike is in motion. I am staying out of the center of the lane for now, just in case someone wants to pass me if I stall out again. I am going to keep riding the bike for a while longer and see if it gets any worse before contacting my dealer. Fortunately, I don't ride during commute hours.
I had exactly the same problem with my GPR-S. It would stall occasionally when coming to a stop. But with that bike I had to wait exactly 3 minutes before I could reboot the controller. I finally got a controller programmer and discovered that it was seeing a "contactor fault". Which, unfortunately, I was never able to resolve.