I just got my S4 a couple days ago and while I'm at work I leave it in Vibrate mode. I noticed that when I receive a text message from anybody it only does 2 short bursts. Most of the time I don't hear it and only notice I have a next text message from the LED Indicator. I have tried going into contacts and setting the vibration there for "basic call" which is longer.....but I still get 2 short bursts. I have gone into the phone settings and set notifications for "basic call" and I still get 2 short bursts. I also tried setting different vibrate patterns for different contacts and still I get 2 short bursts What am I missing? and how do I fix this.