'AS' column-alias beign ignored on outer select

Hi!

Is this the expected behaviour?

select ID
, USK_RATING AS USK
from (
select ID
, USK_RATING
from MAIN_SONY_PS2_GAME
where ID = 101400
limit 1
)
as PRODUCT_LIST
limit 1;

id | usk_rating
--------+------------
101400 |
(1 row)

Note the column-header being labeled 'usk_rating', not 'usk'. Obviously
the 'AS' column alias of the outer select is being ignored in the
resultset.

select ID
, USK
from (
select ID
, USK_RATING AS USK
from MAIN_SONY_PS2_GAME
where ID = 101400
limit 1
)
as PRODUCT_LIST
limit 1;

id | usk
--------+-----
101400 |
(1 row)

If the column alias is being declared in the subselect, the column alias
is working.

select version();
version
----------------------------------------------------------------------
PostgreSQL 8.1.0 on i686-pc-linux-gnu, compiled by GCC gcc (GCC) 3.2

Is this working as expected or is this a bug?

Kind regards

Markus