Hey bro :-) it could come from the heat, but since it was not so long and the plant itself looks a bit darker, I hope that it doesn't start with a blockage :-). To be on the safe side, I would not completely flush the next 2 pouring processes, but pour a little more, adjust Ph and Ec to a quarter dose, that should help :-) Keep going so it will be great 😎🌱