Purple stems and leaves, ld say is the blue genetics coming through, they will darken more while in flower. Looks fine to me from what l could see. I get red stripes on leaf stems and stalks but its my strain showing boldness imo. Keep her growing and dont forget to post further into grow. Could feed one higher ppms if your growing a few, see if it takes it away, not sure though so ld play safe and keep on same road. Genetics can do strange shit. Its not always grower error, except in my case, l can kill the healthiest plant, and then bring back for a good harvest lol. Keep it up your ok, post in a week or so if no change. Dont stress the little things, they are all little things.