That sucks. The same thing happened to my friend. He was running around, found a shiny Geodude... And killed it. He told me that his game was "messed up" but when I told him what really happened and the chances of it happening he rage quit Pokemon Fire Red for a month. :P
In my Pokemon Black I got shiny:
Shuckle, Chimchar, Larvesta (from the egg), Turtwig, Shellmet.
I think my game was rigged. I was never even looking for any shinies. They just randomly popped up out of nowhere. :)