plant looks lush, so i doubt your fertilizer is missing something. Without calculating what you feed, this becomes a wild stab in the dark. Calculat ppms of your nutrient mix and eliminate possibilities.
interveinal chlorosis is a sign of a multitude of things, all of which could be caused by lockout and not the symptom of defiicency you see.
also, could just be shedding 2 lower leaves... if it doesn't spread i wouldn't worry.