Logs not Rotating

I have something like this:

redirect_stderr = true # Enable capturing of stderr into log files.
log_directory = 'pg_log' # Directory where log files are written.
log_filename = 'postgresql-%a.log' # Log file name pattern.
log_truncate_on_rotation = false # If true, any existing log file of the
log_rotation_age = 10080 # Automatic rotation of logfiles will happen after
log_rotation_size = 1 # Automatic rotation of logfiles will happen after

But my logs are not rotating at all, is there something I should be aware of?

PostgreSQL 8.0.5 on i386-redhat-linux-gnu, compiled by GCC
i386-redhat-linux-gcc (GCC) 4.0.2 20051125 (Red Hat 4.0.2-8)

I also did pg_ctl restart, and pg_ctl reload

TIA