How come after a few $http requests my web app stops responding?

I'm making a little web app that has a queue on it, my entering queue code looks like so:

Angular:

 $scope.leaveQueue = function() {
     $http.defaults.headers.post["Content-Type"] = "application/x-www-form-urlencoded";
     $http.post('/user/queue/leave')
     .success(function(data) {
        if (data.hasOwnProperty('success')) {
          $route.reload(); 
          return $scope.user.inQueue = false;
        };
     });
  }

  $scope.enterQueue = function() {
    $http.defaults.headers.post["Content-Type"] = "application/x-www-form-urlencoded";
    $http.post('/user/queue/enter', $('#enterQueue').serialize())
    .success(function(data) {
       if (data.hasOwnProperty('success')) {
         $route.reload(); 
         return $scope.user.inQueue = true;
       }
    });
  }

My backend with Node to handle said queues are like so:

router.route('/queue/enter')
  .post(function(req, res, next) {
    if (req.user.isLoggedIn) {
      req.app.get('pg').connect(req.app.get('conString'), function(err, client, done) {
         console.log(req.user.user_name, req.body.game, req.body.mode);
         client.query("INSERT INTO queue (user_name, user_game, user_mode, created_on) VALUES ($1, $2, $3, $4)",
                      [req.user.user_name, req.body.game, req.body.mode, new Date()], function(err, results) {
          if (err) { return res.json({'error': err}) };
          return res.json({'success': 'Entered Queue Successfully'});
        });
      }); 
    };
  });

router.route('/queue/leave')
  .post(function(req, res, nex) {
     if (req.user.isLoggedIn) {
      req.app.get('pg').connect(req.app.get('conString'), function(err, client, done) {
        if (err) { return res.json({'error':err}) };
          client.query("DELETE FROM queue WHERE user_name = $1", [req.user.user_name], function(err, results) {
             if (err) { return res.json({ 'error': err}) };
             return res.json({'success': results});
          });
      });
     };
  });

My problem is, if I enter and leave queue one too many times, my requests start to become infinitely pending and won't resolve till I restart my node app.js I have no idea why this is happening to me everything is returning a response wether there is an error or not so I'm not sure why it just leaves hanging and then works fine after a restart.

I'm not sure what is causing this, I'm new to Angular I'm not sure if I'm using $http incorrectly. Any information AT ALL would be nice. Thank you.