I had a creepy one like this happen to me with Linkedin. I sold my uncle's guitar on craigslist using a throwaway gmail address to a guy with a very unique, rhyming name that I would never forget (ie - Gerald Herald). Immediately after he left with the guitar linkedin suggests I add him to my professional network. I never logged in to linkedin from that gmail, never looked this guy up, don't have linkedin app installed on my phone, literally met him for 60 seconds to get cash and hand over a guitar. It still weirds me out.