Not unless IG4 is doing something strange. GPS has no idea what direction you are facing, nor does it care. It knows position and that is it. Not speed, not direction, but position.
So all GPS programs I know of measure 2 points with a known time. Line from first point to second point is direction. Distance between them divided by the time is the speed and so on.
So if you happened to get a position location "behind" you, IG4 will think that is the direction you are going. But I am sure they use many more than 2 points and an average so you dont bounce around.
So basically in conclusion, the only thing causing this is a lack of signal. If it is covered by metal slightly so 1 of the sats comes in by reflection, that could be enough of a time difference to cause a shadow behind you. Put the receiver outside your car open to the sky. Drive for a while. If you dont get turned around anywhere, you know why.