peak OPK before period?

Ok so I took a PT 3 days before my period is due and it said negative

Well I decided to take an ovulation year (my last one) for the fun of it at this point since I’m thinking I won’t be pregnant anyway..

Well I used a clear blue digital one and got a solid smiley face..

Why?? Is it detecting pregnancy? Is it because AF coming?

Has this happened to anybody?