I got an iPhone 6s Plus about 3 weeks ago and today it randomly turned off. I left it on the table and when I walked back 5 minutes later it was off. I pushed the power button and it wouldn't turn back on. I pushed the home and power button at the same time and again it wouldn't turn on. I kept trying this and right as I was about to head out the door to the Apple Store, it turned back on. Any ideas what's going on? Should I go to apple?