Mystery part on sunglasses holder

[Cyndrix]

A few days ago a small black piece of rubber with adhesive on one side started sliding off the little latch that locks the overhead sunglasses holder into place when you shut it making it so I couldn't shut it.

I couldn't figure out exactly where this piece of rubber came from, so I just removed it.

Now I have a rattling noise that comes from the sunglasses holder, so I guess that piece of rubber was there to prevent it.

I'd like to secure it back into place to alleviate this annoying rattle. Can anybody tell me exactly where this little rubber piece is supposed to go?

Thanks.