@S&W59: Most anodized aluminum will fade over time. I believe that most anodized parts that have not been coated or painted OVER the anodized surface with another protective layer are designed to last 10~20 years. If a part fades evenly, it's a good thing, it means it has been well taken care of.
The amount of fading depends on the environment it was kept in, and on what it came in contact with (sweat, oil), and parts from two different batches may not fade at the same rate.
If you do a lookup on something like "anodized aluminum fading...", you will find more detailed explanations why and how it happens.
A badly deteriorated or pitted part can be de-anodized, then polished, or blushed, or bead blasted, and then re-anodized. You can remove anodizing yourself, polish the part, and then send it to a professional to be re-anodized in your choice of color, but it may still not match the original color exactly, and may not last as long as the original factory finish, or look the same.