Did I miss my LH surge that quickly??

Ok so I have been using OPKs this week to keep an eye on my cycle after coming off BC a few weeks ago. Yesterday’s afternoon opk was close but negative, so I took one this afternoon around 4 and it was a blazing positive. The test line was darker than the control line, there was no question it was positive. For curiosity I just took another one (3 hours later) and it’s not as dark, the opk scanner on Glow auto-filed it as a negative. It’s definitely not as dark as the control line and nowhere near as dark as this afternoon.

What happened? I know some people have quick short surges and some have longer ones... but 3 hours?? I’m new to opk testing so sorry if this is a dumb question