When I got home, I pinned part of the hat out, then hit it with steam from my iron. Voila - the curl just about vanished!
So....I am grateful for ya'll! I'm also glad I won't have to frog....2 color purl rounds just do NOT amuse me. :grin: (For what it's worth, the curling is still not as bad on the spot I steamed as it is in the rest of the hat. It's there - slightly - but I am hopeful it will recede with proper blocking and i-cord)