Opk experts! I have a question? What does this mean?

Hi! I'm pretty sure I ovulated last Thursday but for some reason (I don't know other than curiosity) I took an ovulation test I had left just to see and this is what I got.. The test line is way darker than the control line immediately.. This is considered a positive opk right? Any ideas why I would get a positive opk a week AFTER I ovulated?