Slide Topper on a 2019 coachman Mirada 32ss

Seems like you discovered another reason to go over anything attached to the outside to make sure it is tight. Once yearly after you check the roof just keep working your way down to ensure everything is tight. Things come loose from heat/cold cycles, sometimes they are not real tight from the factory and sometimes they pull out for no known reason. Your brackets may have been just tight enough when the unit left the factory but use and vibration from going down the road loosened the screws enough to let things come apart. Never assume that all factory and dealer installed items are as tight as they should be, especially brackets and screws making wire connections.