10 miles can make a lot of difference, especially when you prolly have more salt in the air from the ocean breezes - the condensation happens because of temperature and humidity differences night and day - in the sun the air in the cab warms and gets as humid as the ambient, cools at night and the warm air inside dumps it's moisture where it meets the suddenly colder metal, droplets run down behind the double panels and collects in the pocket above the window - try keeping it outta the sun when parked during the day and leaving the windows open
"rust free California" ain't all it's cracked up to be, depending on which way the breezes blow!
Bill