I have a 2014 Ram 1500 4x4. When the cruise control is on, the little green dial at the bottom of the dash reads higher then the actual speed by about 3-4 mph. The actual speedometer is reading correctly. If I`m going 60 mph the green dial is reading around 63 mph. Anyone have a clue. I bought the truck used so I don`t know if this is something recent or it has been like this since new. Anyone?