It could be that the system is still learning your usage patterns and since the phone is still brand new it is still learning how to best optimize your phone by analyzing your usage patterns.
Basically checking the apps that need to be ready for action and those that don't.
Once it figures that out, you should get more juice out of the battery.
Also check your auto optimization settings. Especially the part that says "Restart when needed"
Yes it could be. Damaged battery is the worst case scenario. Here in the Samsung Members app, Click on Support > Diagnostics> Battery. This will check the health of the battery. Make sure you are using the latest software for the phone. I'm really hoping it's software related. But if it is the battery, then take it to the nearest Samsung repair centre to have it checked out.
