Yep that's probably the truth of it as per paul's reply! It will be a graphite based grease hence it looking black. just for your assurance I have never seen grease turned black in the hub before unles it went in black! I tend to use a graphite EP grease for the added luricant effect of the graphite. It is hard to keep that lower suspension area clean. Keep all your holed socks and cleaning out the lower spring/pin area is made much simpler! use them like an American shoe shine boy!