Argh! Knitting mistakes

I was continuing with slow but steady progress on the moss and ferns cowl when I hit a snag.

Here, everything looks okay -- horizontal rows of pink and gray with diagonal rows of daisy stitch.

And then we have the opposite side, in which the top row of pink daisy stitches is inexplicably off kilter:

See how it's sort of between the gray stitches?  How did that happen?

Mistakes like this are painful.  Progress in knitting is always slow, but I can be patient as long as I'm moving forward.  This kind of mistake -- where I have to pull a couple of rows out -- is a real test of my persistence...