She was with Zeref for a bit of time I thought. So I wouldn't be entirely surprised. Zeref did know she wasn't actually 13.
Makes sense.
Also, if there's one thing that I really liked about this chapter, it's that people from outside the main cast are getting a chance to shine. Normally, especially this far into the series, there'd only be focus on one particular group or family and everyone else would be shoved into the background (Saiyans in Dragon Ball, Uchihas in Naruto, Squad Captains in Bleach). One thing that I really like about One Piece and Fairy Tail is that they generally use their supporting cast well.