That is very interesting, its weird I have never heard anyone mention that this happens, I never noticed it happening on my first grow, but these are autos and seem to be sensitive.Here's something that you might find interesting, because i did when i read it for the first time.....I read that the reason that the leaves droop like that, is that the plant has had it's fill of water. When the leaves are pointing upwards they are arranged in a way the directs rainwater towards the center of the plant, funneling water towards the main stem, and vice-versa.