too much oil can can over heat and damage box as the clutch baskets etc rotate above oil normally,rotating at 2-3000 times a minute with parts hitting oil would generate heat and damage ,its not unusual for auto while towing on hot day for light to come on ,it may mean some fault but just as likely be nothing to worry about ,check oil level and drop a capful out if black clutch burning out is generating heat ,less heat will be generated if car can be driven fast enough for torque convertor to lock