Normal
I had this before... The rubber sills for one of the six injectors had worn out and it became brittle. Thus when fuel is being injected, some of it vaporizes out of the rubber sills. So I resorted to changing the injector... Wouldn't take the risk of the car catching fire. After all, fuel in vaporized state is in its most combustible state. Couple that with the heat inside the engine bay, you know what might happen next.