User blog comment:FairyRaven/Fairy Tail Chapter 366: 1000 Souls, Review and Commentary/@comment-3424593-20140109153851/@comment-1359322-20140110035235

Yes Natsu was serious about that test but if we consider it with the seriousness that he uses in his fights against enemy or opponent, it would be somewhat lacking, the time with Gildarts was Natsu focusing on just beating Gildarts to pass the test not beating Gildarts to the point where he can't continue battle.