Second chance pool, it's been a feature since before your account was created. It's a list (second link below) of submissions that didn't gain much traction and gets drawn from to add to the front page periodically. They get an artificially inflated ranking and temporarily changed submission time (which impacts ranking) to give them another chance.

https://news.ycombinator.com/lists

https://news.ycombinator.com/pool - Your submission is on the third page here

https://news.ycombinator.com/invited - Another way old posts come back