This looks like you purled that first row with the black yarn instead of knit it.
If you feel brave you can ladder down and use a crochet hook to reknit that singular column of stitches. It is relatively easy to do but very intimidating at first, especially with colorwork like this.
I really like tutorials by Roxanne Richardson, who I believe is a master knitter. Here is how she explains the ladder down method.
Otherwise you already know ... Frog it.