Facebook looks at your phone contacts, recent calls, and saves that info. It does the same for your colleagues. Another possibility is that your co-workers ar

Facebook looks at your phone contacts, recent calls, and saves that info. It does the same for your colleagues. Another possibility is that your co-workers are browsing your public profile details without adding you. Really you're leaking identifiable data all over the place. There's no way to tell what Facebook picked up on.