About half an hour ago, exactly 41 Nice Question badges were awarded almost simultaneously. I received 4 for questions which previously had 9 votes. So either someone is going around being nice, or there is a bug.
As msh210 has said, it was primarily a single user that voted for questions with a score of nine.
However, the pattern doesn't look malicious and said user could have read the questions (mostly) in the award timeframe.
Hopefully, the badges will spur their recipients onward to more "Nice Questions" :)
I have no reason to think it's not someone looking for questions with nine votes and upvoting them, but only someone with access to the database can know for (more) certain whether there's a bug here, so I suppose we'll have to await such a person (a SE employee) to come along and reply to this. Meanwhile, no harm, no foul.