do evap lines always occur once a test dries?

here's why I ask. I've taken countless tests over the last 6 months of TTC. NONE of them have popped up dark evap lines after they've dried.

The one I took this morning (11am) looked negative. left it out and just kind of creeped on it throughout the day (yeah, I know it's invalid after the window).

either way, went to look at it probably 15 minutes ago and there's this super dark, line glaring at me.

none of my other tests have done this once they've dried?