pg_* Tables

Howdy,

Environment:

Solaris 10
Postgres 8.3.3

I'm getting high sequential scans for some pg_* tables:

<database>=# select relname, sum(seq_scan) as seq_scan,sum(seq_tup_read) as seq_tup_read,sum(idx_scan) as idx_scan, sum(idx_tup_fetch) as idx_tup_fetch, sum(n_tup_ins) as n_tup_ins, sum(n_tup_upd) as n_tup_upd, sum(n_tup_del) as n_tup_del from pg_stat_all_tables group by 1 order by 2 desc limit 4;
relname | seq_scan | seq_tup_read | idx_scan | idx_tup_fetch | n_tup_ins | n_tup_upd | n_tup_del
---------------------------------+----------+--------------+----------+---------------+-----------+-----------+-----------
<table> | 6896498 | 91295702 | 107663 | 469057 | 103966 | 103966 | 103966
pg_authid | 3119053 | 125950392 | 12000732 | 12000718 | 1 | 1 | 0
pg_am | 2642438 | 2642440 | 5 | 5 | 0 | 0 | 0
pg_database | 1349020 | 14771768 | 6953392 | 6953392 | 0 | 0 | 0
(4 rows)

<database>=#

Is this normal? Is it advisable to index pg_* tables?

Thank you,

Sam