Does not sound normal. Dark colouring usually means either metal to metal rubbing (dark grey to black staining) or dark brown to black, which indicates that the oil is burning (carbon staining). It is likely you are running too lean/hot and on a new engine this is terminal. Follow the manufacturers instructions, use the run-in fuel recommended, and if you are unsure get help from one of the club members whose engines always start, never seem to need ground needle tweaking, are still running when the model lands, and still runs funny old engines he purchased years ago.
Evan, WB #12.