problem with ORDER BY

Hello,

I do not understand why the following ORDER BY statment does not work
as I would expect:

1) I defined a simple table with only one column, containing urls:

mon=> \d url
Table "public.url"
Column | Type | Modifiers
--------+------+-----------
url | text | not null
Indexes:
"url_pkey" primary key, btree (url)

2) I populated it, some urls starting with https, others with http

3) When I want to sort them, I get this "strange" ordering:

mon=> SELECT * FROM url ORDER BY url asc ;
url
-------------------------------
http://imag.fr/
https://gmail.com/
https://mail.google.com/mail/
https://www.sixxs.net/
http://www.google.com/
http://www.google.com/reader/
http://www.google.fr/
http://www.postgresql.org/
(8 rows)

Should'nt I get these values in the following order ?

http://imag.fr/
http://www.google.com/
http://www.google.com/reader/
http://www.google.fr/
http://www.postgresql.org/
https://gmail.com/
https://mail.google.com/mail/
https://www.sixxs.net/

Thanks,
--
Nicolas