I don't have a badge on that page so I'm assuming someone liked what they read and copied it to Stumbleupon.
Has anyone else experiences this? I mean the traffic is just mental. The only thing is, I've read time and time again that SU traffic is just junk traffic. I don't understand it completely but it seems people thumbs up or down the content then Move onto the next article. They might just visit your site for a few seconds.
So what good is SU traffic?