Doug,  many copper salts are greenish in color (especially in the presence of
water). It could be copper sulphate, copper nitrate or copper chloride. A
chemical analysis can show what salt is on the pins. Then you can look for
the source of the contamination in your assembly line. One more thing, where
exactly you are seeing this green growth? is is in the contact area? are your
contacts gold plated? I have seen this type of field corrosion several times
and was able to locates the source and eliminate the problem at my
ex-employer.

Please call me if you want to discuss.

Pratap Singh
RAMP Labs
(512) 255-6820