Blower Motor

When I replaced my blower motor resistor I noticed some rust on the blower motor. The motor still works fine. Is this rust because water is leaking from above?

http://i136.photobucket.com/albums/q197/jsnevets/IMG_3618.jpg

http://i136.photobucket.com/albums/q197/jsnevets/IMG_3617.jpg

Some times the moisture from peoples feet gets on the interior of the car causing a humid environment that causes rust.