Are you talking about pigment on the nose and lips (and under nose where skin is)? This is good and indicates the pup will have good pigment. Pigment often fills in slowly in very young pups, such as the 4 wks. one you are asking about, so the other pups may fill in as well as the weeks go by. The breed standard reads "Nose - Black and fully pigmented." and "Lips - Black"