The phone is getting warm when you use anything with a constant Internet Access. Like Pandora, DI.FM, Facebook Messenger (God awefully written application, stealing your info constantly.) Remove Facebook Messenger and use the web app version. You're privacy won't be as violated, and you're phone won't get as hot as the web version isn't constantly downloading information from your phone in real time.
And what you guys are calling hot, is not HOT, it's warm. Trust me, I've had phones that could fry an egg on it literally. The Pixel XL does not get HOT. Only warm by phone standards. This is normal, and most likely will not harm the phone. It's designed to warm up some at the speeds these phones run. In fact, if you are feeling warm its a good thing because the heat is dissipating away from the chip that needs to stay cool, and going into the case which is designed to take the heat away from the chip.
The S7 Edge can almost fry an egg on it, it's pretty HOT, and the Note 7 could nuke an egg lol.
