Welcome to iMore! I could make so many jokes about what you mean by your AppleTV being "hotter" since the upgrade
If we're talking about temperature, I haven't noticed but I don't really touch my AppleTV. It makes sense though because more power is being packed in and adding apps means that it has to work harder than previous AppleTVs thereby generating more heat. If it isn't getting so hot that it's burning you when you touch it or pick it up I wouldn't be too worried about it.