That could have been rust. Many times when solvents are used to take all protection out of the bore, you can not leave the rifle sit. If you still get light rust color on your patches, swab the bore over and over with oiled patches. I find that Barricade removes a lot of fouling. Also Breakfree CLP will remove fouling and rust. So I would swab with that. When you stop getting rust on the patches.. then run a dry patch or two to pick up the excess oil.