I never said to ignore it. Just be patient with him and work on it. It’s clearly a mature thing. He may be a little insecure but many guys are, even when they are older. 

When I say play it off, I mean don’t say it infront of him, choose your words correctly, don’t escalate it, etc. 

Let him know there’s no reason to feel insecure. 

Also, this shouldn’t be enough reason to have your gears grinder, as you said in your OP, there are others things so I can guarantee those other things are triggering this response.