okay this has happened twice now.. the first time i let it sit for about 4 days without being cranked. it smoked for about 30 sec. then stopped. never does it when i drive it on a regular basis. it happened again the other day. this time it only set for 3 days. what gives? should i be worried about this? it never does when i drive it daily, just when i let it sit.. the smoke seemed white but not really sure..