pg_atributes index space question

Hello,

After a VACUUM FULL I saw that pg_attribute tables indexes haven't
been deleted as reported by a subsequent vacuum analyze. But the pages
corresponding to just the table has been deleted to 196 pages from
about 181557 pages. Are all system tables affected by this ? How can
we reclaim this space without shutting down postmaster ? Is this fixed
in any new release ?

db=# select relpages, reltuples from pg_catalog.pg_class where
relname = 'pg_attribute';
relpages | reltuples
----------+-----------
196 | 9965
(1 row)

db=# vacuum verbose analyze pg_catalog.pg_attribute;
INFO: vacuuming "pg_catalog.pg_attribute"
INFO: index "pg_attribute_relid_attnam_index" now contains 9965 row
versions in 181557 pages
DETAIL: 1518 index row versions were removed.
181263 index pages have been deleted, 20000 are currently reusable.

thanks