I've found news.ycombinator.com in my referrers but when I search for the domain on HN, nothing shows up. How likely is it that someone submitted my website and then the submission has been deleted by the OP or by a mod? Is there a way to find out?
OPs can delete links for a brief time after submission. Mods will sometimes change links to a better source of the story. Also the auto-mod system will mark certain links "dead" based on various signals. It could have also been linked in a comment (I suspect that's the case here).