This morning I quickly returned home after 5 minutes driving to collect my phone that I forgot. Turned off the engine - left the side lights on and popped inside the house. Tried to start the car again, it ran for about 2 seconds then cut straight out dead. It did this a few times, so I left it alone a while and it started OK and seemed fine. Is this a normal thing? Could be something to do with the immobiliser I suppose?