unexpected RULE behavior

Hi,

I did the following:

CREATE TABLE data (id SERIAL, title VARCHAR);
CREATE TABLE data_copy(id INT4, title VARCHAR);
CREATE RULE make_copy AS ON INSERT TO data DO INSERT INTO data_copy
(id,title) VALUES (NEW.id, NEW.title);
INSERT INTO data (title) VALUES ('test');

database=# SELECT * FROM data;
id | title
----+-------
1 | test
(1 Zeile)

database=# SELECT * FROM data_copy;
id | title
----+-------
2 | test
(1 Zeile)

and wondered about the result in the table 'data_copy'. I expect the row
with the same values but 'id' is different although only 'data.id' is a
serial but not 'data_copy.id'.
My database is PostgreSQL 8.2.4 and runs on Windows Server 2003.