Hen putting sticks on her back?

Could she be broody ?

Thanks so much Aunt Sally and AL Hathaway, I think you've answered my question - I went back and watched the hen displaying this behaviour, Rosie, and she went off to lay a perfect egg. Since doing so the behaviour has stopped. Because I'd never spotted any of my 3 doing this before, I thought it was an indication of stress for some reason, but reading that link I see that it's another way of calming and preparation for laying.
Many thanks for your swift replies. I can now rest easy and remember that hen keeping is an adventure where you're learning all the time!