Everyone: THIS IS NOT THE CAR RUSTING. As some have already pointed out...
What you see is completely normal and routine; and especially noticeable on white cars. They are rust specs on the paint, kicked up by the tires as you drive. It's a standard part of winter driving and similar specs can accumulate year-round from other sources like industrial fallout and rail dust from train tracks.
The way to undo this is to detail the car. A clay bar is one way to pull these off. You certainly do not need to make a warranty claim to repaint the car, the paint is fine and not causing this.
2012 YB Focus SE Sedan [featured in Performance Ford, Sept '14]
1992 BW Grand Prix SE Sedan [restomod project]