I would think something may be wrong with the test if it took longer than usual for the liquid to take action across the test screen. I'll also say it's easy for our eyes to deceive us a bit if we are prone to worrying a lot. I had a scare where I was spotting so I went out & bought 4 more tests, taking them every morning for 4 days & most people say it was just me but I thought some lines were lighter than others too??? Everything turned out to be okay, I'm hoping all is okay for you too!!!
Oh, another thing. Someone told me they had heard that your 2nd urine of the day is actually the better one, so maybe that's why the test you took at midday was darker than when you used FMU?