Look closely, and you'll see the brown leaf edges that are indicative of heat stress. This damage looks alot like nutrient burn, except it occurs only at the tops of the plants closest to the lamps. There's only one cure for this...get the heat away from the plants, either by moving the lamps or moving the plants.
There's a good chance that this bud was subjected to nutrient solution burn. These symptoms are seen when the EC concentration of hydroponic solutions is too high. These symptoms also appear when strong nutrient solution is splashed onto the leaves under hot HID lamps, causing the leaves to burn under the solution.
Many hydroponic gardeners see this problem. It's the beginning of nutriet burn. It indicates that the plants have all the nutrients they can possibly use, and there's a slight excess. Back off the concentration of the nutrient solution just a touch, and the problem should disappear. Note that if the plants never get any worse than this here, then the plants are probably just fine.
Figure 4 is definitely an over-fert problem. The high level of nutrients accumulates in the leaves and causes them to dry out and burn up as shown here. You must flush with clear, clean water immediately to allow the roots to recover, and prevent further damage. The find the cause of the high nutrient levels.