I often find Stella on all fours rocking back and forth when she is excited by just about anything. Today, she seemed to be cheering on Ember until she was done eating her food. I was able to snap some video of it about half way through.
Also, don't worry, I was very close by in case Ember decided to get aggressive. She is pretty good about her food (not bones), but I was ready to spring into action if required.