What was found
DURING CLIMB-OUT OF DTW, THE FWD LAV SMOKE DETECTOR WENT OFF. THE FWD FA INVESTIGATED AND FOUND NO SMOKE IN LAV AND SMOKE DETECTOR STOPPED AND NEVER WENT OFF AGAIN. THE AFT FA REPORTED SEEING A HAZE IN FWD CABIN AND THEN IT DISSIPATED QUICKLY. NO ONE REPORTED ANY SMELL OF ANY KIND (CREW OR PASSENGERS). A/C RETURNED TO DTW FOR PRECAUTIONARY REASONS. GROUND RAN AC FOR 20 MIN WITH ALL SYSTEMS ONLINE GENS, HYD, AIR ECT. NOTED NO DISTINCTIVE ODOR OR VISUAL HAZE IN CABIN OR FLT DECK. INSPECTED LAV BOTTLES AND ALL CABIN EMERGENCY EQUIPMENT. ALL CHECKS GOOD. FOR PRECAUTIONARY MEASURES REPLACED FWD LAV SMOKE DETECTOR