Phone turned off on its own?

[Ayyrock]

So on Sunday during the superbowl I was at a party and for the first time ever I dropped my phone on concrete. I have a hard case so the phone didn't physically get damaged but the case did get a scratch on the upper left hand corner. This was maybe around 7-8pm. Well I didn't end up getting home until around 2:30am and the phone worked fine throughout those few hours. However once I was home I was laying on my bed texting a couple people and I decided to go on instagram. I was scrolling through a few pictures and out of no where the screen shut off. I thought I had accidently pressed the power button but after I pressed it to turn the screen back on, it didn't work. I tried holding it for a few seconds, still nothing. I eventually got a little frustrated and started pressing the power button many times until something turned on. I grabbed another cell phone and tried calling mine and the call went through and rang but my phone didn't turn on or make a sound. I decided to just put it on the charger and fall asleep and hope for the best next morning. I woke up around 8:15am and found that the screen worked again and the phone was at 100%. Just to be clear the phone still had a good amount of battery left the night before. It hasn't happened since then but it happened once and that's enough for me to worry. Any inputs?