Had been driving my Waverunner for several weekends already. While coming back across the lake everything was working just fine. No alarms, etc. While slowing down to come into shallower water toward the dock a sudden puff of smoke came out of the back end. Quite a bit. Was still running so shut it down. Was worried so took it to my local mechanic. He started it up. Seemed to run ok with just a little residual smoke. He could not find anything wrong. Any suggestions on what might have happened? Have been trying to call my local dealer in Muskegon, MI, but can't get anyone to return my call. Don't want to take it in if it is a well known issue or happening.