It may be from the 3G software that the SSID name originally appeared. hpsetup and linksys are common names in this because there are many real AP's with these

It may be from the 3G software that the SSID name originally appeared. hpsetup and linksys are common names in this because there are many real AP's with these names by default and so the 'infection' would spread from multiple points. It would be a miracle if there had only been a single "Free Public WiFi" AP that caused this 'outbreak' to originate and spread.