I have recently seen two of my stumbled posts getting quite a decent number of hits from Stumbleupon, infact, numbering in 500 or so hits alone per post. I usually stumbleupon other pages and in between, sneak my blog post links per 10 mention of other links. Its quite difficult to get traffic of this nature from stumble upon, unless you are a well known person in the social arena. Was this traffic figure an error?