required argument in hook_services_resources definition does not throw an Exception when resource is called without argument

It seems that this should generate an exception. the amfserver_service_sleep method requires an argument of type int. no default is set.
yet when I call the method it doesn't generate the exception.

I get the output from the function (in flash): result: !!!!! amfservice.sleep should fail since no required argument was sent. **data** amfservice says: argument to 'sleep' should be between 1 to 10 , yours was:

function amfserver_services_resources() {  
   return array(
    'amfservice' => array(
      'retrieve' => array(
        'help' => 'retrieves the version of the amfserver',
        'callback' => '_amfserver_service_retrieve',
        'access arguments' => array(AMFSERVER_PERM_SERVICE_TEST),
      ),
      'actions' => array(
        'ping' => array(
          'help' => 'pings the amfserver and sends back the optional message you send to it',
          'callback' => '_amfserver_service_ping',
          'access arguments' => array(AMFSERVER_PERM_SERVICE_TEST),
          'args' => array(
            array(
              'name' => 'message',
              'optional' => TRUE,
              'source' => array('path' => 0),
              'type' => 'string',
              'description' => 'a message you want to give to the server',
              'default value' => 'nothing'
            ),
          ),
        ),
         'sleep' => array(
          'help' => 'makes the php script sleep for the number of seconds provided',
          'callback' => '_amfserver_service_sleep',
          'access arguments' => array(AMFSERVER_PERM_SERVICE_TEST),
          'args' => array(
            array(
              'name' => 'seconds',
              'optional' => FALSE,
              'source' => array('path' => 0),
              'type' => 'int',
              'description' => 'an int between 1 and 10',
            ),
          ),
        ),
      ),
    ),
  );
}


/**
 * service method for the amfserver
 * it's a testing method for the amfserver, provided as an implementation example
 */
function _amfserver_service_retrieve() {
  return "version: " . variable_get( "amfserver_version" );
  
}

/**
 * service method for the amfserver
 * it's a testing method for the amfserver, provided as an implementation example
 */
function _amfserver_service_sleep( $seconds ) {
  if($seconds >= 1 && $seconds <= 10){
    sleep($seconds);
  }
  return "amfservice says: argument to 'sleep' should be between 1 to 10 , yours was: " . $seconds;
}