CASE statement causes unknown node type 723

On a
[PostgreSQL 6.5.1 on i586-pc-linux-gnu, compiled by gcc egcs-2.91.66]
(Redhat) system, I get an unknown node type 723 error when trying to
do a pg_dump on a db, or specifically, trying to select from pg_views
after creating a view with a CASE statement.

To duplicate:
in any database (e.g. template1)

=>select * from pg_views
(Returns the expected results)

=> create view die as
=> select
=> CASE when usename = 'postgres' then 'something'
=> ELSE usename
=> End
=> from pg_user;
(Creates view 'die')

=>select * from die
(Works fine, but now....)

=>select * from pg_views

root=> select * from pg_views;

ERROR: get_ruledef of die: unknown node type 723 in
check_if_rte_used()

Is it a bug, or am I doing something stupid?

Thanks.