positive opk cycle day 9

I got a positive opk on cd 9. this is my 2nd month ttc, and last month I only got to bd on the 10th and 15th, my predicted ovulation being the 14th. this is my first month using an opk so the positive I got on the 9th surprised me. feeling pretty confident about this month. but my question, is it possible to get a false positive on an opk? since I got a positive does that mean I definitely ovulated probably cd 10?​