She could just be showing signs that she is about to be broody be not quite yet. When she starts to sit on the nest ALL DAY LONG then she is fully broody.
She is broody, she wants to hatch some babies. They will only get off the nest once a day and you will rarely see her do it, they will often have odd large stinky poops. If her eggs are fertile you can put some under her and she will incubate them and hatch them in 21 days. If you don't want her...