I think it's just a natural leaf discoloration. I had the same kind of spot on my Blackberry Cake and it happened only on one leaf on the whole plant. Nothing to worry about. If you want to compare your spot to mine and see how my plant ended, here is the link to my diary growdiaries.com/diaries/182640-grow-journal-by-smokingtiki/week/1042187, see picture named "D22 - Blackberry Cake - Leaf spot". Good luck with your grow đ
you don't need to worry this is normals in a plants early stage (: the first leaves often look a bit deformed or spotted. you should keep on growing and check the bigger fan leaves later on đąđ good luck and sweet smokes