i have a test, that i seen the line when it first came on the test before 2 minutes but didn't really pay attention because i thought it had to be darker. now i can see it better since it's dry and it's definatly a thin blue line. i heard evaporation lines don't exhibit the color of the dye. that they are usually grey? is this true?

That's true, an evaporation line will simply look sort of greyish. The blue is the result of a chemical reaction and is definately there, faint or not. Congratulations?