Here is a photo of my Showgirl rooster (Silkie and naked neck cross). The ear lobe is lighter in color than the rest of the blackish/slate colored skin so the result is a blue ear lobe. Both males and females can have blue ear lobes.
yes that is normal. several breeds have colored earlobes. on silkies they are blue and are part of their standard, if one doesn't have blue earlobes i think its a disqualification either that are a serious fault if you plan on showing.