"Please don't post on HN to ask or tell us something (e.g. to ask us questions about Y Combinator, or to ask or complain about moderation). If you want to say something to us, please send it to hn@ycombinator.com." -- https://news.ycombinator.com/newsguidelines.html
^ I'd do that if you really want an answer.
If they were all pinned to the bottom I would wonder. But they're not. Some of your recent comments are middle or top. Comment position is some combo of points+recency and might factor in overall recent karma.