User blog comment:Miskos3/Fairy Tail Episode 247: Tartaros arc: Alegria, Review/@comment-1359322-20150822101709/@comment-7418318-20150822153636

There is speculation that it was due to her being a Celestial Spirit Mage, especially in light of what'll happen later (probably in the next episode - but please don't discuss that yet due to spoiling anime-only viewers), but at least in the manga there never was any proof so it's anyone's best guess.