Question about evap lines?

I have taken probably hundreds of pregnancy tests (LOL)...all dollar tree.....and I will ALWAYS look at the test a couple hours later and there is NEVER a line....Well, I took one this morning and sort of glanced at it, but not very well....And then I threw it away. Well, I looked at it a couple hours later and there was a faint line! I have NEVER had an evap line..why would I have one all of a sudden? Did anyone experience this..was it a BFP or an evap?? Thanks!