Is D&c Necessary For Mild Bleeding?

I am 55 years old and have had no bleeding for almost 3 years. About 2 months ago I experienced symptoms of ovulation. Tender breasts, sensitive nipples, clear vaginal discharge (quite a bit for about a week). Had my yearly gyn exam about 2 weeks later. All seemed fine. Pap results good. 2 days after visit, I had some mild cramping. It felt like the "old" days of getting my period. Next day small amount of bleeding which lasted 5-6 days. I called my gyn. I had an intravaginal and pelvic ultrasound done. It said that my uterine lining is 6mm. My gyn wants to talk to me about having a D & C. Is this really neccesary or would it be safe to have an in-office biopsy done?