While waiting for a flight to Hong Kong, Arrowtown's Justin Eden noticed a security guard at the airport with the sign.
His wife told the post office manager, who called the Arrowtown community constable.
The post office is one of the most photographed buildings in the village so when the old-fashioned sign was stolen in January, Lakes District Museum director David Clarke promptly had a new one made at a cost of about $300.
Mr Clarke said the museum has been running the post office since 1991 ''on a shoestring'' and was annoyed about the sign's disappearance.
The village's CCTV cameras failed to identify the thieves.
Arrowtown community Senior Constable Beth Fookes said the sign
ended up in the airport's lost and found department. She presumed tourists with a van stole stole the sign and failed to get it on to a flight.
Mr Clarke said he expected the sign to be returned, but ''how it's getting back I don't know''.
