Is this behavior a sign of broodiness?

She is walking around puffed out, pecking at the other hens, and making a lot more random vocalizations than usual. Earlier she made a noise that sounded like the chicken version of a super-exasperated sigh crossed with an "alarm squawk" even though there were no hawks or predators nearby. She laid an egg today, and otherwise seems healthy. She is a ten month old buff orpington. I haven't noticed her sitting in the nest box excessively, which is why I'm not sure if this is broodiness or something else.