Dye on the test...

Okay so i tested today (dollar store U-check) and i was watching the dye "run". When it reached the "T" a very faint line show up for like two seconds and when it reached  the "C"  the line was gone.
(I'm 11-12 dpo now) 
What does this mean? Have you <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a>r seen this too?