Did you go to some petition on change.org from an email link? Because a lot of those petition sites will magically autofill that stuff from the AKV.WERq235FCASDF (or whatever) hash on the end of the link. Probably connecting that hash to the info in their database from when you used that email address before.

The other thoughts I have are maybe you have autofill on in your browser? IDK if you're using the Tor Browser Bundle or your normal browser routed through Tor. (Autofill should be off by default in the Browser Bundle.)

I don't use change.org so I don't have any more concrete ideas than that.