Frame rust recall

Had my '07 frame replaced three years ago at my Maryland dealer. They completed the work in two days and there were no post-replacement issues. I was surprised that it had rusted because I was always careful to flush the frame with high pressure water after driving in bad weather. I treated the new frame with special paint (something called "Hinderust"), using an extender wand to access inside the frame. It dries with a dull green finish.
My TRD access cab is approaching 200k miles. No new rust thus far. Except for the frame, the truck has been exceptionally trouble free. Have used 5W-30 fully synthetic oil since the first oil change. I change oil every 3750 to 4000 miles and never need to add oil. Replaced water pump and serpentine belt at 100k miles, had brake and transmission fluids changed periodically, and changed differential oils as needed. Hoping to keep it running until my Cybertruck arrives in a year or two.