Hi!

Maybe the innards of the thermostat are still wet?
Or there is some soap or corrosion inside?

I have my doubts. I could get the enclosure to come away from the
sidewall of the fridge and everything inside sure seemed to be dry.
What I could see of the switch showed it to be a largely open design.
An area at the back allows some (very little) air into the
compartment.

I doubt that they are made to be immersed in
water.

It would have to put up with some degree of moisture caused by the
opening and closing of the door. I tried to stay away from it with the
washing wand and did not use high pressure.

Since it seems to be running fine, I'm not going to worry about it.

William