Picked up my Model S100D on March 31 2017. The next morning on my first drive of the day, I heard a noise and felt a vibration in the front end like I was going over those small rumble strips that they put down to slow drivers down, but the road was/is smooth. It lasted about 5-6 seconds, and reoccurred again shortly thereafter for a couple of seconds, but never happened again the rest of the day. Basically the same pattern has occurred each morning, and, with one exception does not occur again during the day. The one exception was on highway at about 65 mph, and was not as loud or pronounced as in the mornings; that one might have been the road, but it was very similar to the other occurrences. Called service, and they want me to bring the car in, which I will do. But since I can't reproduce the problem at will, I fear they will have a hard time trouble shooting it. Anyone have a similar problem? Ideas?