I have noticed that my sons crf230 puffs out a little blue smoke on hard deceleration (like he is engine braking down a long steep hill). Bike runs great and doesnt seem to smoke any other time, nor does it seem to consume any oil. Is this the beginning of an issue, or not something to worry about? Bike is a 2008. We are 2nd owner. Bought it with original tires, so bike shouldnt have more than 100 hours total.