Iconfinder is one the most popular ones around... so probably whoever is "responsible" for it used that kind of search engine.
There it is: http://www.iconfinder.com/icondetails/8844/128/kit_settings_... with author, licence and all the info.
We care a lot about stating the license clearly since it's essential to our business. Also if there is anything copyright infringing on our site we'll remove it immediately. As far as I can tell, this icon is created by the Oxygen team and the license information is correctly presented on our site.
If you know you were used for this, you might be in a position where you could choose to help out. There may well not be any clear evidence you were used in this instance though.