Placing my canopy way too close to LED cause what appeared to be a localized iron or zinc deficiency. Raising the light instantly cured the problem. Trust me, it wasn't light bleaching, this was a whole different animal.
My belief is that either cell division rates were outstripping the plants ability to uptake certain elements, or, given that my LED unit produces different spectrums of light from individual diodes, and thus must be a certain distance from the plant to "blend" the spectrum, the light was too close and the plant received a very unbalanced light source, possibly affecting nutrient uptake.
I've seen snippets of info dealing with this and LED's but nothing conclusive. I'm certain the same principles would apply to HID light. Though, at too close with HID's I just get bleaching rather than localized deficiency.