mobile

So, I just exchanged my s6edge for a new unit today because the old one had an issue with tone unevenness and extreme yellowing in certain areas on the screen. Anyway, on my new one when I just click the power button to check the time or notification's, not unlocking the phone or anything like that, the display just sits powered on on the locksreen. doesn't time out or turn off. I have to do it manually. Idk why this is happening all of a sudden as it never happened on the old one or any other phone I've owned for that matter.

Any ideas?