permission denied for tablespace pg_global?

Hi.

I'm looking at the strange phenomenon....
--
C:\Program Files\PostgreSQL\8.3-beta1\bin>psql postgres postgres
Password for user postgres:
Welcome to psql 8.3beta1, the PostgreSQL interactive terminal.

Type:  \copyright for distribution terms      \h for help with SQL commands      \? for help with psql commands      \g
orterminate with semicolon to execute query      \q to quit
 

postgres=# select *,oid from pg_catalog.pg_tablespace; spcname   | spcowner | spclocation | spcacl | oid
------------+----------+-------------+--------+------pg_default |       10 |             |        | 1663pg_global  |
  10 |             |        | 1664
 
(2 rows)

postgres=# SELECT pg_size_pretty(pg_tablespace_size(1663));pg_size_pretty
----------------13 MB
(1 row)

postgres=# SELECT pg_size_pretty(pg_tablespace_size(1664));
ERROR:  permission denied for tablespace pg_global
postgres=#

/END

Have I overlooked the present specification change?
or can someone suggest?

Regards,
Hiroshi Saito