I agree its a bug that sucked the goodies out of that part of the leaf, do be watchful.
My pat response to it is a light coating of spinosad insect soap on the pot surface, not a lot.
So far so good. You can also hang a sticky trap
See what happens
That mark looks like a pest issue to me. Nothing sever but enough to keep an eye on. If it gets worse an organic neem oil solution can help protect your girls! Happy Growing! ✌️😜