question about log entry from trigger execution

I have a database I inherited with a number of triggers defined on various tables.

One AFTER trigger, when executed, causes a database log entry with a "CONTEXT" entry, but no ERROR. I normally only see the CONTEXT entries when an ERROR occurs.

The trigger is on table rbs, and it returns NULL.

Here are the entries (slightly edited):

May 5 16:08:21 postgres[18723]: [598-1] 2010-05-05 16:08:21 UTC LOG: statement: DELETE FROM rbs WHERE id = 136259855 AND cid = 601
May 5 16:08:21 postgres[18723]: [599-3] 2010-05-05 16:08:21 UTC CONTEXT: SQL statement "UPDATE uinfo UI SET id_bitmap = (id_bitmap & ~(1::bit(128) << (C.bitmap_index
May 5 16:08:21 postgres[18723]: [599-4] - 1)) ) FROM cinfo C WHERE UI.id = $1 AND $2 = C.cid"
May 5 16:08:21 postgres[18723]: [599-5] ^IPL/pgSQL function "rbs__adel" line 6 at SQL statement
May 5 16:08:21 postgres[18723]: [600-1] 2010-05-05 16:08:21 UTCLOG: statement: COMMIT

The statement that seems to be logged is:
UPDATE uinfo UI
SET id_bitmap = (id_bitmap & ~(1::bit(128) << (C.bitmap_index - 1)) )
FROM cinfo C
WHERE UI.id = OLD.id AND OLD.cid = C.cid;

The update seems to get done ok. I still wonder what the log entry is trying to tell me.

This is PostgreSQL 8.3.

Any ideas?

Susan