Does this seem right?

Yesterday morning my opk was positive at around 10:30am. I tested again at around 4pm but it had gone a little lighter, making it negative but still high?!

As for yesterday evening I had cramps etc which I normally do when I ovulate. Seems odd my test was lighter tho!

Could I have had a positive during the night whilst I was asleep and that’s why it seemed a short surge as I tested late in the morning also?