A downvote on a 4-day-old comment...
Is not possible since they turn downvotes off after 24 hours.
/pedant
As someone who incessantly refreshes HN and spends a fair amount of time on the Comments page, I see no reason why it wouldn't be people seeing new comments to older discussions via the Comments section rather than bots. Although I am a demographic outlier in multiple ways, I cannot possibly be the only person routinely cruising the new comments section.
