It could be that someone read just the first line of your comment, realized it jived with their view, and upvoted before continuing on and finishing reading the

It could be that someone read just the first line of your comment, realized it jived with their view, and upvoted before continuing on and finishing reading the rest of your comment. If HN stores timestamps of upvotes in the backend we could confirm (i.e. upvoting within milliseconds of submission = bot)