droopy tips

600w hps enclosed w/glass

fan blowing at light
fan blowing at mary

the tips of the topmost of the plant moving downwards seem to be drooping downwards a little. What is this and how do I remedy this.
Ps....everything else looks awesome

need some pics if u have

I do not have a cam to post. The plant has great growth. Lush and green. I recently topped it a few times. I just noticed that there are 2 leaves (of a shit load) that seem to be curling down at the central vein. Not curl even, just like /\ <---thats the leaf...lol

what do suggest this is? How to counter?