She appears to be molting, some do it sooner then later. You'll also notice during molting her comb will look smaller and less red, so keep an eye out for it. Very normal. May also receive a lot less eggs from this one as a poultry change gears from egg laying to feather growing. She should be back to normal in a few weeks. Miss having RIR's..they have that look in their eye like one will distract you while the others sneak up behind you. =)