Those are probably old style parts... if they get transitioned to the new system that outline should go away.

More info:
For old parts, the decoration texture image included the design and the base color for the part. Back in the day, the decoration texture image is what was used to color the part. You could NOT change the color of these decorated parts. As Scrubs upgraded the system, he built in an algorithm that removes any color from the decoration that matches the base color of the part. This is what allows you to change the part color now. However, the algorithm isn't smart enough to remove the blended pixels where the base color touches other colors of the decoration. Only the parts that are fully the base color (or very close) are removed, and the rest are not touched. So this is where the outline comes from.