Given than one of the IP addresses I was given reverse-resolved to "adsl-69-111-95-106.dsl.chic01.pacbell.net", which I assume is a consumer DSL service in Chicago, I think you're right to have reservations.

EDIT: I got the same three IP address from a host in the continental USA, and from a host in Australia; I imagine it's just serving the same three hosts to everybody. Be afraid. Be very afraid.