Xperia Z2 :: Screen Didn't Light Up

Today as I was listening to the radio (thru an app), i wanted to unblock it and the screen didn't react, I could rise and lower the volume and I tried to plug it to the charger and the light that appears when charging, worked too but the screen kept being black.

I finally decided to press the little red button next to the Sim card and the phone started working fine again, in fact I'm writing from the device, but i wanted to know if I shud worry about this happening (it was the first time ever), or maybe was it because it heated up because I used the radio app too much?( I used it during the morning for like 2,5h and in the afternoon 2h more...