A little dart will do ya: Jalie 2921 Women's Scarf-Collar Top
It worked! I sewed a dart into the center back collar piece and tapered it into the center back seam of the bodice. A somewhat crude correction considering how this collar is attached to the bodice, but it gets the job done.
I really like this top and I will sew it again- but I will re-draft the collar band and I have to think about the construction. Thanks for your ideas!! It was a quick fix!