Firstly, as with all the other mails, it's good to see that your okay.
I have also flown the Gazelle and came very close to the phenonmenm (?) know at the time as 'Fenestron Stall'. This was investigated by sending aircraft to Eurocopter in France where the Test pilots span them round in small circles for a couple of days.
The huge amount of data they collected boiled down to the fact that the Fenestron was not 'Stalled' but had reversed airflow around the tips in spite of the shroud containing the blades. These conditions were most likely to be reached during:
1. A rapid or sudden demand for a left turn.
2. Wind from the right.
The onset is rapid and indeed very scary! Especially for a Gazelle beginner. Subsequently I have flown a large variety of helos and can say that the Gazelle rates up there as No.2 for fun factor!
Flying is a risky business and it is only through work, and the disemmination of information and experience that we can continue to make it safer.
Good luck and have many more hours fun flying the Gazelle.