I have not driven my mondial in about 3 months, but I have it started once a week and let it run for about 10 min. For a while now, a great deal of normal (not black) exhaust comes out of the 2 left exhaust pipes only. It comes out for about 3 min but once the motor is hot the exhaust goes away and everything seems fine. Whats going on? Why is the exhaust only coming out on the left side? Should I be worried? Thanks in advance.