How did I have a negative score?

In my current game against "Anna" I thought I had a point. When I just took my tun, I won the round. When it went to the score, it showed my score change from a negative 1 to a zero. So I won the round and have a zero. 

I have another post open about the same person. In that post I let you know that when you play any round with her, it appears that she did not answer all songs in that round correct because the first star is not full. That usually means it is their first time playing that playlist and the missed one. But if you go to her stats, all playlists are almost completed. 

I have not deleted her yet because I would like for y'all to know there is a problem and where to find her. 

Thanks,

Angel