Thanks for the help/kind words. I think heat stress is a likely candidate. Not from the light to close (they are 36" above the canopy) but maybe a mixture of a little too long between watering and the low humidity here making the heat a bit more damaging. What do you guys think? New growth is still very healthy, and it did hit the leaves closest to the light not the lower ones which does point to heat stress. The White Crack really is taking off in size so it might have been a bit more desperate for moisture than the rest.