Not trying to be argumentative so please don't misunderstand. The flow switch is at the end of the circuitry far, far behind lots of other stuff that would go up in flames long before a couple of contacts burned due to lightning. I should have lost the controlling PIC, any one of a number of other components including the micro amp tolerant LCD display if lightning hit the power or any of the control circuitry to the system. I also have about 25 other logic based devices inside the house and they haven't had any failures. Much more likely is that they don't have a capacitor across the contacts to suppress the arcs or that they are putting too much current through the switch.
Granted, lightning does strange stuff at time, my neighbor lost a large cactus last year to it, but only this one component going out is too weird even for that.