Gotta remember , Ciel, they don't really have much of a brain. They run on instinct and
sometimes it doesn't work. I know with dogs once in awhile you will get a super mom,
an alpha female. She will do everything just right to raise those pups.
Mine proved she wasn't operating on a brain . She picked up a small pup sized ceramic duck and put it in with the pups and tried to nurse it !
Your hen is just being weird , like my dog.