What should a US citizen with a retirement visa know about re-entering Thailand after a short trip to the USA?

I just got back from Los Angeles. I'm an on OA. The process currently is Thai Pass, Mandatory insurance, Test/Go or ASQ packages booked before TP application and then of course the mandatory 72 hour RT-PCR test before flight. Arrival process at BKK was very quick. Landed at 0830 from Singapore and was out the door and into the hotel van by 0915. If your visa or Ext of Stay is current then the biggest unknown is the insurance. The DC Thai Embassy or anyone of the Thai Consulates have the required information on it's websites.

Probably not needed saying, but ensure your current visa/extension does not expire while you are there, or it's back to "GO" for you.

Make sure you have purchased a REENTRY PERMIT BEFORE you leave Thailand.

If you are fully vaccinated..

You can do the Test N Go entry.

You need to apply for a THAILAND PASS to be able to reenter Thailand.

You will not need to contact any Thai Embassy or Consulate in the USA as you already have a valid retirement extension of stay stamp in your passport.

You will need to get the required health insurance...or show proof of it....

What is your age?

Your most up-to-date source would be your local Thai consulate. There's 5 Thai consulates in the USA (if my memory serves me right), and the consulate you'll use is the consulate within your region.