Default [Q] Nexus 7c serious screen problems

hi everybody.

first time posting a query here.

my Nexus 7 has been plagued by this problem for about a few months. assuming it was a bug, waited till the 4.4.3 update arrives.

have updated it, but the problem still persist.

the video is at youtu.**be/**bZLHorAuScw (just delete the *)

any ideas on the cause of the prob?

anyway, the device is still a virgin (have yet to be rooted) and has never been dropped. only use it to play games, watch movies and read ebooks and pdf files...

thanks for all your feedback.