Trigger for Audit Table

I'm asking for a sanity check:

This is a very simple audit table setup where I use a BEFORE UPDATE
trigger to save an existing record.

The table stores templates (for a CMS) and looks something like this:

create table template (
id SERIAL PRIMARY KEY,
path text UNIQUE NOT NULL,
content text NOT NULL,
last_updated_time timestamp(0) with time zone NOT NULL default now()
);

And then an audit table:

create table template_history (
id SERIAL PRIMARY KEY,
template_id integer NOT NULL REFERENCES template ON DELETE CASCADE,
path text NOT NULL,
content text NOT NULL,
last_updated_time timestamp(0) with time zone NOT NULL
);

(The "path" is not the primary key because the template's path
might get renamed (moved), but I still want to track its history.)

My trigger is very simple:

CREATE OR REPLACE FUNCTION audit_template() RETURNS TRIGGER AS '
BEGIN
INSERT INTO template_history
( template_id, path, content, last_updated_time, person )
select
id, path, content, last_updated_time, person
from
template where id = 1;

RETURN NEW;
END'
language 'plpgsql';

CREATE TRIGGER template_history_add BEFORE UPDATE ON template
for each row execute procedure audit_template();

I realize this is a *BEFORE* UPDATE trigger, but I have this vague
memory of seeing a post stating that you can't be sure the existing
row has not been updated yet. Perhaps that was just a concern if
another trigger was to modify the row. But, I can't seem to find that
post now which is why I'm asking for the sanity check.

Are there potential problems with this setup?

--
Bill Moseley
moseley(at)hank(dot)org