no, it's not carrying a virus. For facebook, are you using the app or website? as for the wifi, it depends on what type of setup your library has.... I know at work, we use peplink devices to grant wifi access and all my windows 10 devices (950, Surface Pro 2, Lenovo Yoga 2 pro) would not log into it UNTIL we updated the firmware on the peplink routers/access points/equipment.
Having done IT at a library for 8 months, they may not always be up to date (in case you are wondering why 8 months, I quit as it was quite possibly the worst job ever. huge library in a city means NASTY people and employees, both physically and mentally)