laravel pusher webhook always fails due timeout

I am using Pusher webhook of types presence and channel existence, and locally I am using ngrok to proxy the requests to my machine. whenever a webhook request is sent to my local server then it gets received and return 200 status code in ngrok, but, for that exact same request I see "webhook failed due time out" in Pusher debug console. I timed my controller execution using microtime(true) and usually it takes 0.05325984954834 which is lower than the Pusher 3 seconds timeout. what is the problem? how to solve it please?

Here is my code:

  public function channelExistance(Request $request){
        // return response('ok', 200);
        $start = microtime(true);
        if($this->requestValid($request)){
         foreach ($request->input('events') as $event) {
            $name = $event['name'];
            $channel_name = $event['channel'];
            if(stripos($channel_name, 'presence') === false && stripos($channel_name, 'private') === false){
            if($event['name'] == 'channel_occupied'){

               $this->manager->channelStarted($channel_name);
            }
            elseif($event['name'] == 'channel_vacated'){
               $this->manager->supporterIsFreed($channel_name);
            //    return response('ok', 200);
            }
        }
   }
}
$end = microtime(true) - $start;
    logger('time taken: '.$end);
    header("Status: 200 OK");
}

via Chebli Mohamed