I pointed out to my dealer at the first service that the cam chain tensioner had been superseded by Yamaha, they had a listen and ordered the new part there and then.
Took about a month for the part to arrive, during which it go so bad that the bike sounded like a black hack.
Replaced a few hundred miles ago and everything's been fine since.
I had the same scenario...mentioned it in passing while we were stood chatting in the workshop and the next thing I know...my service manager was booking the bike in to have it changed and had already Ordered the superseded part...has been sounding as it should ever since it was replaced... 800 miles ago...