Gildartz is incredibly powerful. He made the most determined and hot blooded guy in the manga admit complete defeat. That's unheard of when talking about Natsu. The difference is strength was just too immense.
Gildartz does care for Natsu a lot however, he knows that he has the potential to surpass him, and is going to play a big part in Fairy Tail and the dragon's future.
3 chaps next week sounds AMAZING! First one is called "Mest" so either we get a glimpse of him in battle, possibly already victorious, or something else revolving around him, possibly a conversation with Wendy regarding his backstory. I think it's a safe bet that the 1st exam will be over by next week.
Cana and Natsu have already passed, Mest is practically guaranteed, Fried's out, and the others are unpredictable. Elfman and Lluvia were having trouble against their respective S-Class Mages, and Gray and Levy's hopes vary depending on who got the quiet path between them and Mest. Next week will be great for Fairy Tail.