You have to give it to Apple when it comes to cosmetic details. Not many (if any) tech company can be compared with Apple when it comes to tiny details.
For this case, someone who has installed iOS6 noticed that the little knob on the iPod Slider is actually “reflecting” light when the phone is tilt around. Apple actually manipulate the graphics to let you have the impression that the phone is shifted or changing position. This is super minuet details. Kudos to those Apple engineers and designers.