You know I know nothing about Harley Sportsters. Now that's out of the way, I had the exact same thing happen with my K75. It only happened when it was very hot - riding along, the engine would cough a couple of times, then dead. Always restarted, sometimes without even coasting to a stop. To make a long story short, it was a hall effect sensor that sent an engine timing signal to the electronic ignition. Probably not the issue for your "older" technology....just trying to keep the trip alive! Hope its something simple.
PS: DA has been given a complete bill of health! No worries!