anyway I've renewed online, so technically I'm legal again even if I get pulled over before the tabs arrive. And cops are pretty lenient for me anyway... I'm white-passing. :P
@fluffy From what I understand, senders can pay to have a piece of mail returned to them with the new address instead of forwarded if they use the "return service requested" note on the mail, so that might be what happened.
https://pe.usps.com/text/qsg300/Q507.htm
@SimonTesla That explains how the charities got my updated addresses, but it doesn't explain how the Washington Department of Licensing didn't get their very important obviously-to-me mail forwarded. I should probably contact USPS and ask wtf is up with that.
just to be on the safe side I've also printed out the proof of renewal on the very unlikely event that I get pulled over driving up the street to the grocery store