I had this happen with my own submission yesterday[1], which wasn't a Show HN. Was sitting at #5 for a few hours, then suddenly dropped to page 2.

It was all healthy discussion, not a flame war. Actually would've been better served by me not responding so quickly.

Currently at 52 comments, 43 points.

[1] https://news.ycombinator.com/item?id=8094684