We have 6 chicken all about 27 weeks old. The Barred Rock, Buff Orpington, GLW Wyandotte and RIR are laying and the Brahma and Easter Egger are not yet. The odd behavior is with the RIR. When she's in the nesting box she grabs mouthfuls of pine shavings and dumps them on her back... Like she's burying herself. Then she gets up they all fall off and she starts all over. Is this normal???