User blog comment:Sargenttacos115/Natsu and Gajeel age Theory/@comment-67.176.8.202-20140625231700/@comment-122.49.159.37-20140626093104

And Erza was able to pass through the runes after they were put up. She was frozen by Evergreen, but when she was revived she was able to go out and fight.

Also, pretty sure Gray doesn't say that Natsu's younger than him, but that he's been in the Guild longer than Natsu but Natsu is more powerful.