Oh you're right, I forgot about that.
I actually used an opk this morning, which I know isn't the best idea but I wanted to poas and I have loads of opk's. Anyway, the test line was about half as d dark as the control line. I expected a faint line as I know there usually is on an opk but this was unmistakable. Unfortunately I dumped out the cup I peed in so couldn't retest with an hpt in the same sample. Got me thinking though!