The issue with predictable is that most who are act out of habit and are less flexible so changing is rare. That teacher most likely noticed what most teacher notice that you didn't know, understood what has been lecturered and cannot bring it into practice. The only way to test that was by changing the questions. Sounds like he succeeded.
He really did.
Everyone was stunned and disappointed.
I barely made it through the exam myself but I learnt a valuable lesson on the process.
This is what all teacher here do. They give you the former exams to practice with but it is never the same so it is pointless to count on the same questions. Great you passed.
Thanks.