Bad air flow?

I have a speaker growbox. At the bottom there is a fan that blow air in, it goes outside it self on the top. The airflow is weak, but for a small autoflower i have, it is enough.
But i am woried that there is no other fan, and the plant itself or the leaves aren't moving at all. It's on a 40th day from seed now, and it looked healthy, only a bit late in growth, but now it got bushier so im worried.
So how important is the movement of the leaves? not the air flow, but just the movement.

flow does really gets Co2 moving threw your box and also makes it so the plant is stronger. thicker branches and more sturdy and overall healthier

well it strenghing the stem..if u have air coming in and out just not blowing on ur plant..itll grow itll just most likly be weak. might have to stake it up for flower. GOOD LUCK

if there isnt movment in the plant it wont be able to hold the buds... you NEED a fan!!!!!