Maybe it's an Indiana thing. In the fast lane, people seem to (subconciously) slow down when they pass a truck or other slow moving vehicle. Then they pull over after they pass the truck, so that you can get past, but they speed up by 10 mph. Makes me crazy. I've seen a few a-holes that do it on purpose, but mostly I just think it is stupid Hoosiers who haven't figured out how to maintain a constant speed.