I've talked to some of the other guys on here about this and it seems to happen to a few here. I've just learned to deal with it. And yes. It was making that faint sound since I bought it new. I have a 2017 S.
I have a 2017 manual trans with the same noise. It sounds like when we put thin tube headers on cast manifold V8s in my youth. I am guessing that the sound is from the thin tube exhaust manifold. An exhaust leak is more of a tick sound. I filled with a tank of 93 octane to check if the sound is detonation and the sound did not change, so no, not detonation.