probably fluctuating pH -- this causes varying growth rates in the leaves, so you get waves/warping etc.
the paling of the top leaves are mostly likely something else, but i'd ensure pH is relatively stble (within +/- .2 is probably good goal, and ok to do better than that too). Once thta's stable for a bit, and you can observe new growth after that point -- if it looks fine it was probably related to the pH .. if it continues to reference a leaf chart and make your best guess like anyone else... at the least, paling from in to out on leave is one of the more distinctive symptoms.