iPhone 6s Half of the screen goes dark and gets back normal

I recently bought my iPhone 6s, like 3 days ago, and it caught my attention that the screen brightness is changing, most of the time the right side brightness is what it should be, but the left side get much more brighter and some times it flashes, I will add a picture of it as well. I made a reservation to apple genius bar, but so far I haven't seen anything like that shared by other user in the internet. I was wondering if anyone else ever encountered anything like this. If so any heads up.