I duuno maybe I missed the mark but
a) some here say he slipped out of tune and just went with it. That assumes you were listening to a live performance (which it certainly was not). Since it is a recording (which I assume it is).......
b) I personally think the guy was going for a bold move to be creative and I was not all blechhh about it. Was it "strange"? Yeah, but what is so wrong with that? Pedro will probably like it. Wait..... never mind.