You may want to raise the PH and try to sweep the ranges 6.3-6.8.. You may be seeing the beginning signs of locking out mag. Keep an eye on them and don't stress... You are in good hands here...
I think I'll be paying attention to this issue as I may be in the same boat. Also getting a soil pH like 6.0 - 6.3 and the plant's seem a little too limp.