Odd sort behaviour

Since when does "." sort as "nothing at all"
This select
   select           distinct u.user_name   from           subscriber_user u,           subscription s,
subscription_templatet   where           u.id = s.subscriber_entity_id           and s.template_id = t.id           and
t.application_id= (select id from application where   short_name ='books')   order by u.user_name   \p\g
 

over this table def.(for user_name)
    \d subscriber_user             Table "public.subscriber_user"   +-----------------------+---------+---------------+
 |        Column         |  Type   |   Modifiers   |   +-----------------------+---------+---------------+   | id
            | bigint  | not null      |   | last_name             | text    |               |   | first_name
|text    |               |   | user_name             | text    |               |   | email_address         | text    |
            |   | force_password_change | boolean | default false |   | title                 | text    |
|  +-----------------------+---------+---------------+   Indexes:       "subscriber_user_pkey" PRIMARY KEY, btree (id)
    "idx__subscriber_users__lower_email_address" UNIQUE, btree   (lower(email_address))
"idx__subscriber_users__lower_user_name"UNIQUE, btree   (lower(user_name))   Foreign-key constraints:
"subscriber_user_id_fkey"FOREIGN KEY (id) REFERENCES subscriber(id)
 


is producing this sorted??? output

   | adrianohazim@hotmail.com                   |   | adx008@show.org.tw                         |   | aecheniq@mac.com
                         |   | a.ecke70@gmx.de                            |   | aelefant@unina.it
  |   | aeo_tw@hotmail.com                         |   | a.fischedick@t-online.de                   |   |
aflores3432@gmail.com                     |   | afried@advancedneurosurgeons.com           |   | agave007@comcast.net
                   |   | agelsinger@amirsys.com                     |   | agis1doc@yahoo.gr                          |
 

using this client
   Welcome to psql 8.3.7, the PostgreSQL interactive terminal.

and this server
   show server_version;   +----------------+   | server_version |   +----------------+   | 8.3.7          |
+----------------+  (1 row)
 
   nsm=# show server_encoding
   +-----------------+   | server_encoding |   +-----------------+   | UTF8            |   +-----------------+   (1
row)