Diagonal line on hpt

So i have been feeling like crap today and decided to take a hpt to see if that was the cause. When i took it i splashed onto the window part and a light blue line showed up almost right away. But it was like across the top corner of the results screen. After a min. The control changed color and was way dark. I dont know if i screwed it up or what. (Tried to take a pic but my camera wouldnt pick up the faint line cause i didnt think about it till like 15 mins later.)