I'll bet that the plastic door liner was not present? Any plastic sheeting will do, like a garbage bag. They are required to prevent exactly what you have, because water gets inside the doors when it rains or when you wash the car.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC