Notifications are stopped if
          * The last one was too close
          * We reach a rated limit

def _watchdog(self):
        ''' Notifications are stopped if
          * The last one was too close
          * We reach a rated limit '''
        too_early = (time.time() - self._last_time < self._min_interval)
        too_much = (self._count >= self._rate_limit)
        return (False if (too_early or too_much) else True)