Check the wear on either side of the car. If the left side is thinner, it is doing more work than the right. This would indicate a seized caliper on the right side. Another thing to keep in mind is that if the tires are not evenly worn between the left and right sides, this too could exhibit the symptoms you refer to. If the brakes check out ok, swap your left tires for your right ones. If the pulling follows the tires....well, you get the picture.