Object syntax

Given the following table definitions, and data inserts:

dev=# create address (addr varchar(50), postcode varchar(9));
dev=# create client (name varchar(30), addr address);
dev=# insert into client values ('Michael');
dev=# insert into address values ('11 Windsor Close', 'RH16 4QR');
INSERT 18935 1
dev=# update client set addr = 18935::address;

dev=# explain select client.addr.postcode from client;
NOTICE: QUERY PLAN:
Seq Scan on client (cost=0.00..1.01 rows=1 width=4)
EXPLAIN
dev=# select client.addr.postcode from client;
ERROR: init_fcache: Cache lookup failed for procedure 18935

What's happening here? Bug, or am I doing something wrong?

Cheers...