Minor graphics display problem: internal province border showing as international border

In game no. 1,950,950, I am playing the "Northern States of America," and I have captured all but the final two Canadian provinces in the extreme northwest and extreme northeast. Two of the Canadian provinces I have already captured are "Fort George" and "Schefferville," so their common border is now an internal provincial border completely within my NSA territory. Instead of displaying as a thin gray line symbolizing a provincial border, it is displaying as a dark black line with colored border symbolizing an international boundary between countries.