That is an interesting question indeed.

The filter that was used, selected only posts that had actual text of at least 1000 characters, had less than $7.50 in pay outs (possibly could use a little bit more exposure by using the nobdibot tag) and had not used bid bots. So this is infact a reward based on certain qualifications that you did achieve. So, it is not a blind upvote and you did not pay for it, you earned it, by using the platform in a responsible manner.

Blessings!