I think it's fair to say that all dance lessons start off with a warmup and a stretch before the learning actually begins. That's good! It keeps us safe and healthy as dancers. But what if you have back-to-back classes? You're already warm because of your other class and you stretched at the beginning of that one - why do it again?
If you have back-to-back classes, use the beginning stretch as a cooldown.
Cooldown stretches have a different purpose: First of all, they can be much deeper. Because you have already been working, your muscles are warm and can go further into the stretch allowing you to extend your flexibility. Cooldown stretches relax the body after putting it under strain instead of warming the body up to start working safely.
So - after making sure your instructor knows - change the purpose of the stretch to cooldown before learning more.
Live In Motion,
-Joél Casanova