I have had this happen twice in my first floor laundry room. After the first time, I had a drain put in the floor thru the bottom of a washer pan and put a water alarm next to the washer. 11 months later, the alarm went off and I stopped the machine before my crawl space underneath flooded again. The problem was the cycle size dial was not completely clicked into the specific cycle chosen. Visually, it looked correct, but must have been hit by a laundry basket put on top. Solution is to check the dial each and every wash and listen for the click.