Im not 100%, but that almost looks like a pH issue. Only reason I think this is because on my Da Purps there leaves looked similar. I had a pH issue for a second,but still a few fan leaves did this to me. If Im remembering right cal/mag def.would have some red or we color down the center veins of the fingers. But like I said Im not 100% I don't have my ledger out. Don't take my word as the gospel, Im no pro. Because my pH issue could of caused a cal/mag deficiency lol. Since it corrected itself I just assumed, but we both know what happens when we assume.