Problem setting #default_value for date_popup

Hi I'm trying to set a #default_value for a field which is not accessible ie: #access => FALSE

$form['date'] = array(
  '#type' => 'date_popup',
  '#title' => t('Date'),
  '#access' => FALSE,
  '#default_value' => '2009-06-18 04:31:00',
  '#date_format' => 'Y-m-d H:i:s',
);

But the value ($node->date) I get on hook_insert or hook_update is something like '0009-06-18 04:31:00' or '1009-06-18 04:31:00', notice the first number changed. I ran it through a debugger and found out this, comment on the code

function _form_set_value(&$form_values, $form_item, $parents, $value) {
  $parent = array_shift($parents);
  if (empty($parents)) {
    // here $form_values = '2009-06-18 04:31:00', $parent = 'date', $value = '18/06/2009'
    // thus it's setting $form_values['date'] = '18/06/2009';
    // i don't know where the bug is though
    $form_values[$parent] = $value; 
  }
  else {
    if (!isset($form_values[$parent])) {
      $form_values[$parent] = array();
    }
    _form_set_value($form_values[$parent], $form_item, $parents, $value);
  }
}