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.