I did not see such a warning.
Washing hands is probably a good practice anyway. My semi-educated guess/warning is not due to concerns about manufacture in China per se (stamped metal plus paint isn't particularly hazardous), but more due to moisture & corrosion treatments applied for overseas shipment in containers. Then again, if I bought something manufactured in USA (or anywhere) from my local military surplus store, I'd wash it & my hands too, as I _know_ those items have all sorts of "stuff"! on them for better storage. I wash my hands after using WD-40, let alone more modern stabilizers/preservatives. YMMV.