Hitting the home button doesn't always wake up the screen
I have got a new iphone 6S Plus. Sometimes my iphone doesn't want to wake up immediately after pressing the home button or the power button. The screen stays black. I have to wait for a few seconds.
When I hit the home/power button again the phone usually wakes up or... wakes up and makes a screen shot!
It happens 2-3 times per day.
I have active option "raise to wake" and sometimes it also doesn't work (Sometimes I have to wait a few seconds or additionally press the button).
I tried to make a factory reset from the phone (a new iphone) but it didn't work.
I think that the power and home buttons are working ok when the system is running.
Is it some kind of IOS problem?
IOS seems to get the signal that the home button/power was pressed or the phone was raised but sometimes it doesn't respond immediately.
iPhone 6s Plus, iOS 10.2.1