This happened to me one time. I too start the car occasionally while being stored for the winter. One time I let it sit for a couple of weeks. When I started it, one of the lifters was ticking loudly for a couple of seconds. After research, I determined it to be caused by the oil draining completely into the pan. It took a couple of seconds for the lifter to "pump up." Hasn't happened since. As for the sewing machine sound. Don't get abnormal noises confused with normal noises. These engines are typically noisy. Most of them sound like a sewing machine at idle when standing outside the vehicle. The C32 MB guys refer to the engines as German Sewing Machines.

Hope that helps.