How Do Jared Padalecki & Jensen Ackles Want ‘Supernatural’ to End? -- The Winchester Brothers offer their personal take on what they'd like to see in the ‘Supernatural’ series finale. -- http://movieweb.com/supernatural-series-finale-jared-padalecki-jensen-ackles-ideas/
SEASON 4 SPOILERS I completely agree and at first I wasn't actually sure if it was John or my dog making the sound at the time. But after realising I think it is honestly the best choice of acting for what had just happened.