I'm going to take a completely different route on this. Todd is deaf., but He knows something is going on. I agree, it's not "loud" like those of us can hear type loud. Todd has his own way of making sense of the world. I'm not deaf, but my best guess is that he is feeling some vibrations. And he probably feels them much more intensely that the rest of us who are not deaf. So I'm with Todd, something is wrong. Or at least different.
IMO, I don't think it's tires because he says it subsides when the clutch is pulled in. So to me it's engine / drivetrain. Chain and sprockets would be a first thought. After that, I really think Todd needs to involve a person who can hear if anything is actually going on with the engine.
As far as heat... again, Todd knows his bike. But one thing I find is that even folks who know their bikes do is that they fail to consider ambient temp changes. Remember that a cooling system has a limited capacity to shed heat. If it's 95* ambient, you have to know the bike is going to be close to "fan on" temps in a short time as compared to 60* ambient. Todd, if you recall last year at this time / ambient temp, and you think your bike is running hotter this year, it's time to get the system serviced.
And please let us know if you figure out the "growl".