Lines appear on stucco random times, fade at times, darker at times. About 10" down from soffet, air handler in attic. Always straight line, plumb as can be. Distance varies but leads me to think foam board behind stucco, if used. Interior sheeting completely dry. Mud dobber nests in attic. Quarter size puddles have appeared on concrete patio, at end, black is and gritty. Anyone familiar with this? I've had three stucco companies here, no one has a clue. What's causing it?