Internal catalogs error in log file

I saw this in my log file:

ERROR:  invalid regular expression: quantifier operand
invalid
STATEMENT:  SELECT n.nspname as "Schema",
          p.proname as "Name",
          CASE WHEN p.proretset THEN 'setof ' ELSE ''
END ||
          pg_catalog.format_type(p.prorettype, NULL)
as "Result data type",
          pg_catalog.oidvectortypes(p.proargtypes) as
"Argument data types"
        FROM pg_catalog.pg_proc p
             LEFT JOIN pg_catalog.pg_namespace n ON
n.oid = p.pronamespace
        WHERE p.prorettype <>
'pg_catalog.cstring'::pg_catalog.regtype
              AND p.proargtypes[0] <>
'pg_catalog.cstring'::pg_catalog.regtype
              AND NOT p.proisagg
              AND
pg_catalog.pg_function_is_visible(p.oid)
              AND p.proname ~ '^+$'
        ORDER BY 1, 2, 3, 4;

It's greek to me ;). Any idea what caused this error,
and if there's some sort of problem?

Thanks,
CSN
PG 8.0.2

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