It is nothing to worry about and is perfectly normal/ok and is not nutrient related. Two other things, I would recommend that you water the soil and not spray your plant with water because it can cause fungal problems and having your plant under 24 hour light, in my opinion, is too much. 18/6 is far better as plants do need to "sleep" and you are not gaining anything by having your lights on longer than 18 hours. Cannabis can only grow so much in 24 hours and 18 hours is there limit for extended light versus extended growth. Your plant can not simply use all that light energy to grow any more than if it were only getting 18 hours.
Hope this helps,... Organoman.