Mobile Runner Game random black lines flickering

I am starting to create a runner game. I have done the basics player and game mode setup however, now I am stuck on this issue of having black flickering lines random appearing on the floor. I though was because there was a gab between the attach point when a new tile is created but it seems to be OK. What this could be? Also if there is no light on it the lines are not so visible.

Is this something that can be solved?