So Acura emailed me a satisfaction survey relating to a recent service, and I commented that while I was happy with the service adviser, I was disappointed with the build quality of the car with the gaps and misalignment mentioned in this thread.
A few days later, the service adviser called me and said he also has a 2019 MDX with similar fit issues. I was welcome to bring it back to the dealer where they will try and fix it, though may have to send it to a body shop depending on how far they can take it.
One part of me wants to get it fixed because the imperfection bugs me, but another part of me is really reluctant for them to fiddle with a relatively new car, or take it apart, just because of a minor misalignment with the panels. I've had experience in the past where I've asked the dealer to fix something, and they either screwed it up, or fixed it but caused another problem unintentionally.
I think I'm going to leave it as-is for now, and try to distract myself with other things that are actually important ..