Although, me personally, have never heard/seen that... there's a possiblity some site does it. I've yet to come across one that does.
Everyone who posts here uses the tracker url:
http://useekfiles.com:2710/announce. The site can then keep stats on your torrent. If you don't add the url, it will look as though there are no seeders through this site.
Hope this helps.
If you have any more questions, don't hesitate to ask.
