yeah, thats a deficiency, the only time you would leech for a deficiency is when it was caused by a lockout from too much of another nutrient. they need more calcium. cal-mag is the traditional cure, but theres a product for tomatoes call blossom booster thats pretty much a pure cal foliar spray, and pretty cheap. i'd hit them with that once a week. cal-mag has Mag, N, and iron, none of which is bad, but already present in most nutes, so its easy to over do it if you give them enough cal-mag to satisfy their cal needs