I took a test..false postive?

i took a test this morning..and i read it before the 10 min were up and it looked like a very very faint line was there..and i looked at again after the 10 min was up and the line is now darker i know that means the evap line or something but it looked to be postive before that...has this happend to anyone? i dk if it was too early or not since i havent gotten a period since i had a dnc in july