The relativized timestamps are an artifact of the re-upping system. There are past explanations here: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que....

Sorry for the confusion! I know it's weird but the alternative turns out to be even more confusing and we've never figured out how to square that circle.

There is a comment here by me which says “2 hours ago”, I swear I wrote it longer ago than that - indeed, my threads page still says I wrote it 20 hours ago, so it is like part of the code knows when I really wrote it, another part now thinks I wrote it 18 hours later than I did…