First how old is she? Second we had this problem with Laddy when he was younger and every so often now he will nip. Our solution was to say no bite and put him in his crate and ignore him for 5 min at a time each and every time he bit. It only took a couple days of this to get him to stop. Now he only tries it with strangers and at first sign of it into crate he goes and it stops. Hope this helps.