What Causes Persistent Vaginal Bleeding Post Hysteroscopy For Uterine Polyp?

I had a hysteroscopy 17 days ago to remove a large bleeding polyp. I am still having some bleeding. Not excessive but will get heavy, then almost stop, then next day starts up again, especially with getting up or moving around. I am still on birth control pills so I won t have a cycle until I heal. The biopsies came back benign. I am 53. Is this normal after hysteroscopy?