You didn't start a diary for this grow? Why not?! With no information, we can't possibly be expected to give you an answer... That being said, I would tell you to check the PH of the runoff on that one plant because I think something is out of whack... and each strain and even each plant of the SAME strain can respond differently to exactly the same treatment so you have to "read" each plant as an individual. Put together a diary.... then ask your question again!
Good luck!