Pago Pago Representative Vesiai Poyer Samuelu said when the cheques were distributed he questioned the House speaker about the source of the money but got no answer.
Some lawmakers had said the leaders told them the funds can be used to set up offices in their homes and pay for telephone and internet costs.
The House Speaker and Senate President received US$20,000 while senators and representatives got US$10,000 each.
Tuala uta Representative Larry Sanitoa was the first legislator to return his cheque.
There have been two protests last week over the spending of federal funds for lawmakers' offices.