A couple years ago I was a few feet away when a hawk dive-bombed a young six-month old pullet. The feathers flew in every direction like an explosion in a pillow factory, but when I finally found my pullet, she had a perfectly bald back but not a scratch on her skin. She was lucky, probably because she was fast.
I would bet the hen you are wondering about had a similar close call if she was out free ranging or if your run is uncovered.