Have a 2015 570, quite stock, under 1000 miles. Didn't do this when I first got it, but lately there has been an occasional brief hesitation when just cruising along, after warmup. Today for the first time it actually hesitated so bad it coughed, almost a backfire but not quite. (At the time I was cruising along a paved road at about 55 MPH.) Is this a symptom of the infamous voltage regulator issue, or have I come up with a new one? It only does it once in a while, and otherwise runs great. Suggestions?