I did my first aerobatics on my third flight (second flight was a bit cloudy) and my fourth flight was mostly using trim and taking things more leisurely. Besides, now I am starting to feel much more confident behind the controls. Just being able to keep it under control much better which I think reassured me to be able to do these things.
I didn't know the gliders were that capable! Wouldn't cadet pilots have to pass an aerobatics rating anyway before doing loops etc in gliders? With flying you're with pilots who have lots of hours and are extremely capable. With gliding, and no offense but it's just what I've seen, it is typically cadets who have just achieved the required hours and are then let loose. My friend had something like 15-20 more hours logged than the pilot flying him at a GIC.