We've recently noticed water dripping out of our light switch box in our kitchen. It's on an outer wall of the home. The case itself is starting to warp slightly on the corners, suggesting this has gone on for at least a year or so. We had seen small water lines occasionally under this light switch, but since it's in the kitchen, we always figured it was from someone washing their hands and not drying them before flipping the switch.

We've looked inside the case, and there isn't a significant amount of moisture inside. We've looked at the floor directly above, and there is no obvious sign of moisture. It is about three feet over and 20 feet below our upstairs dryer vent. I got on a ladder last night, looked inside the vent from the outside, and it wasn't overly wet or anything (I was thinking maybe moisture was getting in there and coming down somehow to the light switch. Granted, it also wasn't sealed well around the vent.

Thoughts on why this may be happening? We live in a humid area, but we haven't noticed anything like this on our other outlets or light switches.