Happy growling from a greyhound

This is Tony my beautiful greyhound in 2009. He passed away in 2011 at the age of 10 and I miss him terribly. Tony did something that I have never seen any dog do. He growled when he was happy. If you petted him the right way, he growled like a purring cat. You will see this about one minute into the video. He also does a tiny bit of his happy butt dance at the end but it might be hard to see in this video. I miss you boy.