I think it may have to do with the front alignment and the correct toe-in. I know on my car, a spreader bar must be used on the car to achieve correct toe-in.
I have the same problem as you, but only since I had the car aligned after getting new tires and shocks. I have since had it aligned again, which fixed the problem somewhat. The place I went to does not use a spreader bar, so I'm going to have to make a trip to the dealer soon for a proper alignment.