Yeah, that is definately a Migraine aura (mine looks like a weird spiky ameoba, with rainbow color cycling fractal patterns on the edges).
More info from the site of the Migraine Aura Foundation:
http://www.migraine-aura.org/content/e27891/index_en.html
One thing more, let us know if you experienced any kind of sensory loss afterwards.
A lot of people say they see a bright vibrant pattern at first, like a fractal, or a zig zag, and later see a depressed pattern, like shadows or a blind spot, or sometimes nothing at all (like me, I lose my left peripheral vision).
That would be due to the nature of the aura, an area of the brain becomes hyperactive and expands outward (the hyperactivity... not the brain O_O), leaving behind an area of heavily depressed brain activity.
I hope this puts your mind at ease, you don't need to worry too much about auras, just about what comes after them. They also serve as a good early warning system to go ahead and pop an aleve or motrin (or try a homeopathic rub, like Head-on (see my other post)).
Just please be sure to notice if you vision blurs or something after the hyperactivity passes, I had that thing hit me once while driving, and I had to pull over, thank god nobody got hurt (literally, for me the left side of the world just disappears). I'm just saying, be careful what you are doing when it happens. And immediately pop a painkiller, because the migraine IS coming.