Cold climate fuel selector switch

[NovaScotiaBassBoat]

So winter came early to nova scotia this year. I managed to treat the fuel in the tanks,run it thru the carbs,minst the cylinders etc. Poured some antifreeze in the live wells,floor drains and anywhere else thought might contain water.
Temp dropped to minus 10cel ,ive got my boat in a portable shelter for the winter,when I was checking on it I noticed a large amount of frost around the fuel tank selector and no where else. I have no idea what this indicates.hope my selevtor hasnt frozen and ruptured. Anythoughts

[Fishysam]

the air just condensed on the different type of material differently as the temps changed, outside of a cold can of pop in the summer heat, cold metal warmish air