I've had my kubota for 3 months now and i have seen a few sparks fly out of my l-210 before just one or two once in a great while. today after putting my finish mower on and doing some passes to get it adjusted and used to it my l-210 then all a sudden shot sparks up out the stack. i idled down and more blow out like a cig out a car window on the interstate. the tractor sounded fine, idled fine, and ran normal back to the house. searched on here and also googled it. from the sounds of it all i did was heat the exhaust up enough to burn off built up carbon. but it still has me worried about my ol' girl. is this a common thing?