I took the genset back to the store and they looked it over. On their display model the cap has some movement but not as much as mine. The manager (bless his heart) took the cap off the display and put it on mine.
Brought it home and it still rattles, not as bad but not what I expect from Honda.
I was looking and wondering about swapping out the cap from the old one and noticed if I pulled up on the new cap it kind of locks in place and stops rattling. Not a clear lock a kinda locks. I checked and nothing in the manual about it. Thanks Jim