I agree. Maybe it is a Karachi thing, but moisture always finds it's way. There is moisture in the air and this area is not air tight. As long as it is in contact with ambient air it is in contact with moisture in the air(aka humidity in the air).
Bare metal is extremely prone to rust. Since this is a hidden place, the process may be slow but the edges will surely turn to red-brown color in some time, perhaps in a few years.