I cut off the yarn, unrolled the rest of the ball, rerolled it the other way, and joined the yarn back on. I have only done a couple of rows, but it does look like that was the problem. This will teach me not to trust that two balls of yarn are exactly the same from the store, including rolled the same way

.
The flip side is I was planning to make this a short scarf anyway, for wearing under my coat collar to keep me warmer, and the unmatched part is right in the center, so it won't look too bad I think (I didn't want to pull out those rows)

.