Clearblue OPK

Sarah
Is it normal to get three days (Sunday, Monday, today) in a row of a flashing smiley (high fertility) on the clearblue advanced ovulation kit?? I have had low fertility all last week and then ever since Sunday (when by the books should have been my ovulation date) I had had high fertility. My period is exactly 28 days and very regular. Last period date was February 22.