Curious about Opks

Marie
First month I started Opks and I started early in the month because I didn't know if I was the "average" ... I had no lines to a vvvvvvfl then positive. I tested a couple more days (today being last I believe I O'd yesterday) and I still see lines not dark dark but still visible. Does it take longer for LH to go away than it does to first show up?