Fixed it. I drained all the water out of the tank, unscrewed the drain pipe, cleaned some sealant off the threads, made sure the threads inside the tank were clean, wrapped the drain pipe threads twice with teflon tape, reinserted the drain pipe and tightened it up about 4 revolutions. Refilled tank, waited for drips. Sure enough, got few drips after a half hour. Tightened up drain pipe an additional half turn, drip stopped.