Your pad, if un-coated, will form a patina unique to you and should be looked at as a feature rather than a bug.  Some pads will develop a pronounced coloring, to heavy oxidation, while others do not.  Sweat tends to cause rapid color change in un-coated metals.

If you suspect the pad will be exposed to sweat on a daily basis, we recommend wiping it off after each use with a light teflon oil or silicone spray.  Or better yet, purchase a pad that has been treated with a protective, rock hard gunkote from Greensforged.