False positive on OPK

Beth
I am currently taking estrace for 5 days after my round of clomid. I started using opk on CD 8 and today on CD10 I got a peak reading on the clear blue digital. Does anyone else have any experience with this. Should I keep testing to see if I have another surge. I thought clomid usually delays ovulation? Last month without clomid I got a peak on CD 8. Thanks!