StumbleUpon breaks the rules a bit

In the "I disagree with you, but I'm pretty sure you're not a Nazi" spirit.. I'd like to lodge this gentle complaint about StumbleUpon.

People like the photo I posted yesterday, which is fun to watch the reaction to... but one of the referers that Flickr showed was

http://stumbleupon.com/refer.php?url=http%3A//www.flickr.com/photos/--mike--/5198232631/sizes/l/in/photostream/

Unfortunately, this doesn't actually refer to a StumbleUpon page, and instead feeds me to a generic page about StumbleUpon.

I'd like to know who referred to my photo, and why. It's not unreasonable to want to know what is being said about my stuff.  Referrer fields exist to help give this feedback, and StumbleUpon breaks this social norm.

If the people at StumbleUpon could fix this, it would be appreciated.