FIRST DAY APPROVED AND GOT CHARGED 40?

So today i was just approved to sell on amazon already submitted my bank for deposit and confirmed my taxes, id and all but i just got charged 40 bucks from amazon i know its 40 bucks i believe a month (correct me if im wrong) once i start selling i havent even sold anything and im being charged? was this a mistake can i get more feedback im new to this thanks