I have the same problem with my mac book pro,it used to appear at the lower part only like 1 inch, and I have been looking for solusion for a while, and didn't know what to do so I ignored it .. yesterday it was a little bit slow so I restarted it and the entire screen had lines like if it was broken and the dead pixels are every where !! I freaked out I think I am taking it to a workshop
Though I still think it is a manufactory mistake because my laptop is new and I took care of it