From my experience, I would guess that your head is not symmetrical. And the rain has led the bottom of the crown of your hat to revert to a more symmetrical shape, distorting the brim a bit.One of my VS's is a traditional fedora design. It's been through a couple of rainy events. And though I am meticulous about keeping the brim in shape, there is an ever so slight ripple on one side interrupting the side arc flow. How do you reshape, or 'reset', the memory in the brim area to even out brim arc action?
If I were you (and I did this myself), I would ask Art to make you a band block. Since he has the exact shape of your head, he can make a block that will help keep the headband area in that same shape while your hat dries after a rain event. So no more brim distortion.