Could it be that you supplied that info when registering your domain?
Every domain has a contact address. This is usually publicly viewable by anyone.
(This can be used to settle domainname disputes, report abuse, etc)
Try
this link.
It looks up all administrative information about any domain. This can only be changed by requesting such a change at the company you registered the domain with.
(Note: ofcourse when any information is already publicly accessible, there is no way to guarantee that no copy of it exists, consider for example the Google page database)