I also did a little bit of reading. I think you're right though bro. Zinc deficiency is the most probable issue.
And if we don't look after it then things can go downhill, check this:
Taken from a post at 420magazine forums:
"...These nutrients will get locked out due to high pH: Zinc, Iron, and Manganese...
..With a low level of zinc in your plants, your yields will be dramatically reduced..."
Possible Causes:
"High ph, Low organic matter, High Phosphorus levels in the soil, and or lack of nitrogen."
I also interpolated that the zinc deficiency could be caused simply by a lack of zinc
But from what I read it is more than likely tied to something else. We hardly used any nutes at all on her so I can't imagine our pH is too high but we should definitely check.
Also stolen from this post:
"
Solution to fixing a Zinc deficiency
Any Chemical/Organic nutrients that have potassium in them will fix a Zinc deficiency. (Only mixing at ½ strength when using chemical nutrients or it will cause nutrient burn!)
And any of the following nutrients will fix a zinc deficiency: Zinc sulfate, zinc chelated, or zinc oxides are adequate fertilizer sources for zinc. Or you can bury galvanized nails in the soil. (Make sure you take off the sharp point at the end to prevent roots from being damaged) Garden Manure, which is slow acting. Greensands, Cottonseed Meal are both medium/slow absorption as well."