Maybe you are running a little too hot for the engine to be restarted (vapour-lock).
I know engines like the Flash .12 like running around the 120 mark, and Im not sure about the RB Touring engines, but perhaps 130 is a bit too hot.
Unless you cool the carb down before you restart it, then it might keep happening. Do that, or try to get some better air-flow across the carb, that could help.