I have 3 BAs we hatched. They are 4 weeks old. They are losing down but there is mostly skin w/out mature feathers on two out of the three. Only one seems to have feathered out as quickly as our RIRs. Is late feathering normal for BA chicks? Or should we be concerned? They are healthy, otherwise, and are on a high protein chick starter feed and the three were hatched together (eggs came from a hatchery.)