I noticed that the other night. It seems to be more of a bug in the downloading logic as a whole (meaning that if somehow you were enterred in the download mesh, you'll try to download from yourself) rather than in PFS... but, PFS will cause it to happen at a higher frequency because you actively enter yourself into the mesh. I'm not too positive how to stop it in the NAT'd case though, especially in the setup you mention (which is basically the same as mine).

There's a few other bugs we have to work out as well.