I seriously doubt that you would of heard of it. It's by group called "Luna Halo" and the song is called "complacent"
it's at the very end of the song like the last 20 secs.

And I don't think it's natural/pinch harmonics, and come to think of it it doesn't sound muted, the chord will just be strummed and then it'll sound like it's sliding down then it will stop. DId that help a little more?