Measure the relief ...as in
measure it for consistency. Use a precision ruler: buy one at your local Home Depot or Lowes for like $5, or use a business card, a pick, anything to ensure you are actually seeing what you think you're seeing with absolute
consistency.
Only with this info can you then say that something is amiss with the TR/neck acting like a limp noodle. In which you can call the factory and they can direct you to the closest factory-auth tech that will have the say so should warranty work be required.
Like you, I have been around guitars for quite some time and I have never in my life experienced wild changes in neck relief, even recalling the cheesy imported junk I had played in youth sitting out of its case loooong before I even knew about humidity's effect on acoustics. Tuning changes subtly with changes in RH, but what you're describing seems very strange, indeed. Troubleshoot with measured certainty and see what comes of it
Edward