Next that happens, put it in neutral and try to start it. If it does, you have the same issue I had with my 2012......a faulty transmission position sensor in the transmission. The computer thought it was still in gear enough though it was in Park. Shifted into neutral and it fired up. We were able to re-create this several times, so we were pretty confident it was that sensor.
I had exactly the same symptoms as you. Randomly starting. Started fine at the dealer, until finely one day at a store it wouldn't start and I had to have it towed. It was actually the tow truck driver that stumbled across the neutral thing.