Recently tonight my vibration pattern changed all of a sudden. I had custom vibrations turned on but I didn't create any. I left it on the default Alert vibration. Then out of nowhere it changed. I received a text and it did the heartbeat vibration. I checked the settings to see if I changed it by accident and it hadn't changed. I tried turning off custom vibrations but I am still getting the heartbeat vibration. How do I get the alert vibration back? Is this a bug?