cracking noise from e46 coupe door?

[caramba]

Good afternoon all. Extremely windy this morning, went to get in car and the wind blew the door open too far over. Heard a loud cracking noise. Does anybody have any idea what could cause a noise like that? Without taking anything apart, theres nothing visibly loose or out of place, door and window opening and closing as before. Door brake was probably already somewhat worn, due to the age of the car.