Stange behavior of sort request - Mailing list pgsql-novice

On a postgresql server (8.3.7) I send a request:
SELECT status FROM mytable ORDER BY status;
The result is :
3a
3b
3.
4.
5.
AB
...
With my encoding (UTF8) I expected to have 3. before 3a. Can anyone explain me
this strange behavior ?
Thank you.
Simon GEORGES