One more time immediately go buy a lottery ticket!!
Is this on a concrete floor? If yes that is likely playing a factor given how much moisture is in concrete. I had similar issue with a leak sensor in my HVAC drip pan that all of a sudden started reporting wet. Solved it by putting a small piece of paper towel below the sensor. The paper town provides a barrier but will also absorb the water if there is a leak.
It happened again! This time it was a slug like 1st time. I am thinking some salt on the floor might be an option. I have 2 moisture sensors at this location about 3 feet apart for redundancy and it was a different model of moisture sensor than the 1st. This is not good for WAF. It's like The Boy Who Cried Wolf.
With me it was flushing of the hot water heater and calcium build up from the last flush in the pan that I have the sensor. The calcium held enough moisture when the humidity was high to trigger the leak sensor.
I have 11 leak sensors in my condo.
I am always putting a largest possible piece of paper towel under each sensor.
This actually significantly increases sensitivity area in addition for surface-sensor isolation.