My truck sat all day in freezing weather. When I started it, it sounded like there was a hole in the exhaust. I actually got out and checked the exhaust. I let the truck warm up and off I go. Short ride to the interstate. Roads are icy. As I speed up to 60mph I notice that the truck has that slight vibration like one does when running in 4 wheel drive. It stays like this for about 2 miles then slowly quiets down and the vibration goes away. Anyone ever experienced this?