Howdy Rbacon198, I have been growing i DWC for ten grows and the only time that I have seen an effect like that has been either during the 'lights out' droop, or when the water is drained out of the reservoir at feeding change, or when I had an extreme pH change during an early grow. This may sound silly, but are there and plant ties (from LST) on the branches that are drooping? If there are ties, they may be too tight, restricting the water flow into those branches, if not, then there might be a root problem, like the beginnings of root rot or a critter munching on the roots. If You can, look at the condition of the roots (on the drooping side of the plant).