Does a positive opk, 3 days before period, mean anything?

Several things other: that pre-ovulation can cause a (+) OPK. It can pick up HCG, the pregnancy hormone, since the 2 are chemically similar. Occasionally a woman will ovulate more than once in a cycle. Women with PCOS can have LH elevations thruout much of their cycles. If you don't get your period on time, I suggest you do a pregnancy test. Best wishes. Dr. Anne