You know that thermal paste can be gray without necessarily meaning it has silver right? Where exactly does it say silver? I'm not saying it doesn't contain silver, as most do, but just because it's gray doesn't mean it does. It also has nothing to do with the OP, because you can replace the thermal paste with a variety of compounds.
Not all thermal paste is equal. The included thermal pads are decent for the stock cooler, but when you want better cooling you should replace it with higher quality thermal paste. The silver and other compounds are generally in lower quantities on the stock thermal pads.