Take a look at the partial results of this query:

{
  "timeline_type": "votes",
  "post_id": 2544061,
  "creation_date": 1269993600,
  "owner": {
    // omitted for brevity
  },
  "action": "7 upvotes"
},

I'm sure the answer pointed out by this record never had 7 upvotes and there are no similar records for other answers.

So what does "action": "7 upvotes" mean?