Interesting. Thanks.
My first guess was that Chikuma was fresh from Japan, but that's not the case. She left home waters on 16 Aug; fought Eastern Solomons, then had a space where it looks like she spent 2.5 weeks at Truk before heading out for what became Santa Cruz. That should be enough time in port to paint out the hinomaru, if it's a "home waters only" thing.

As you say, "go figure". There's so much still to learn.