CD 5 unusually dark, almost positive...

Hannah

I have been tracking my cycle with opk’s for a while and I usually ovulate on CD12 (get my positive on CD 11). I just end my period last night and did my first opk of the month and it was surprisingly dark. I took another one an hour later and it was super light like my CD 5 usually are, confirmed again with a 3rd opk. Do y’all think the first was just a dud?