iPhone 7 is uncomfortably warm, anyone experiencing this?

Hello, just wondering if anyone has issues with their new iPhone 7 becoming uncomfortably warm during the restore process? During the restore process, my phone heats up and became warm like a warm paper cup of coffee. It wasn't hot to the point that I'd feel unsafe holding it, but it's rather abnormal compared to the previous generation of iPhones I owned. While charging idly, it is warm too. None of this happens with my other iPhone 6 out of the case. I wiped out my old iPhone and restored it and let it sit charging too. During the restore process for the iPhone 6, it felt warm, but nothing compared to when the iPhone 7 was charging idly without any application opened in the background. Is this normal? I was concerned and brought it to Verizon Wireless' attention. They were helpful and have since replaced the original iPhone 7 with a new one, but the replacement has the same issue. Just because both are consistent, it doesn't mean that this is normal.... but at the same time, it is new too. Are there things going on behind the scene because it's new? I ran Sleep Cycle app on both the 6 and 7 without any apps opened (same apps on both). iPhone 6 lost 23% battery life (from 87% to 64%), while iPhone 7 lost 31% battery life (from 94% to 63%). Both runs on the latest iOs too. I ran Waze and play music in the car, it heats up through the case within 15 minutes use. Never have heat issues with the others I previously owned. It's just strange and am concerned. Let me know if you have the same issue and/or if it's OK and I just have to wait it out?? Thanks a bunch!