Urine confusion with results

So I used my second urine of the day to test with today and I got a flashing smiley face! I'm so excited because we've been having some issues because I'm irregular. Then I read your pamphlet and it said if you don't use your first urine of the day after sleeping at least 4 hours you may get a false high fertility. My question is, if your test detect the surge in hormones why should it matter if it's the first urine or not? If it detects the hormones than that's what it should be. Im going to test again tomorrow but I'm hoping this isn't false, I'm going to treat it like its right but that just doesn't make sense to me.