You saw it on Bitcoinity.org? Can you describe the...what-do-they-call-it...'storyboard' of the animation?
A green bar appears at the top 1/3 of the screen with an animated gif that plays in the center for about 10 seconds.
I had an animation too! Though it was different, and happened the day bitcoin crashed. Phew! I'm not the only one! 
Easter egg confirmed
Easter egg confirmed
Yes, there are several apparently, check Reddit/Twitter. Unclear whether it's just market based or additionally triggered by a timer (as the market wasn't doing SFA when I saw The Matrix one).