Cpt,
I would imagine the floats inflated due to the vibration in the Immersion probe (shorting it out) manifested by the airframe vibration rather than the flector banging against the 'mechanical floor' triggering the relay.
The older Immersion probes were known at times to be the reason for setting off the floats uncommanded due to either sand build up or even water shorting in flight (rain) as well as internal vibration within the probe.