My car sits alot because its not my daily driver and for a while now when i first start it i get a little bit of gray smoke when the car is first started. However the smoke only comes out if i admediately rev the motor right after turning the car on. The amount of grey smoke is very small. What could be causing this? I have a feeling its just because of the cold weather and the car sitting??? you guys have any idea is it anything to be concerned with???