do a search on taco leaves. Number one (but not only) cause is RH. Tell us about your environmental control but at this stage I would just go with it you are still good and healthy. Learn up for next time.
My light is at the very top of tent ive tied entire branches down. I need to bend better in bending next grow. i flush tomorrow and go dark friday im at 8 weeks exactly friday. I dont think it was mag thing. But will learn more next time. These pics are from today