I'm having a hard time replicating this, but sometimes when you switch hair styles during character gen, you end up with a different color. I've noticed this most often going from black -> burgundy, or burgundy -> tan, but have also seen colors switch to pink and various browns. It's usually after switching styles ~12-15 times.
I'm not sure this is a bug, but I'm not a huge fan of how some colors vary drastically between hair styles (i.e. the medium brown option in the hairstyle that's column 1, row 13 (a wavy shoulder-length style) has a green undertone that is . . . startling.