Anyone else encountering a neg SEO attack using AppEngine?

Anyone else encountering a neg SEO attack using AppEngine? ... I am guessing it is a negative SEO attack of some sort. All I know so far is that an AppEngine app out of Russia was forwarding to my website until it ran out of quota. Filled my GWT logs with a bunch of 404 garbage. There is no reason for a cloud app to refer to my web stores. The traffic was only bot traffic... I've been hit before with attacks from people forwarding toxic domains and DOS attacks that interrupt the googlebot crawl of my sites... this one doesn't seem as straight forward.

If you have encountered anything similar I would really appreciate hearing about it.

Thanks,

Ted