Broody chicken?

[albird101]

So today, my easter egger hen layed an egg around 7 o clock today, and she got up and out and then she came back and sat on the egg, every time another pullet or hen would come by she would puff up and bite them but she dosnt screech or anything she dose the same with my dog aswell, but every time i pet her on the nest she squats as if i was a rooster. its already 9 and i went to check on her again and shes still in the nest. do i have a broody? shes 7 months old