date -> text convertion error

I have run into a strange type convertion bug in PostgreSQL. I have a
table with a 'birtdate' field with type 'date'. I convert this to
text to reformat it to a string 'DDMMYY'. A few dates are converted
wrong. The first example moves the birth date from 25. to 24.:

pere=> select birthdate, birthdate::text
from user_appl where fname = 'Antal';
birthdate|text
----------+----------------------
1965-04-25|1965-04-24 23:00:00+01
(1 row)

pere=> select birthdate, birthdate::text
from user_appl where fname = 'Petter';
birthdate|text
----------+----------------------
1973-07-11|1973-07-11 00:00:00+01
(1 row)

pere=>

What is going on, and how can I stop this from happending?

System Configuration
---------------------
Architecture (example: Intel Pentium) : Intel Pentium II
Operating System (example: Linux 2.0.26 ELF) : RedHat Linux 5.2 / 6.0
PostgreSQL version (example: PostgreSQL-6.5) : PostgreSQL-6.5
Compiler used (example: gcc 2.8.0) : gcc 2.7.2.3
--
##> Petter Reinholdtsen <## | pere(at)td(dot)org(dot)uit(dot)no
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