Yes, I would expect to be told. I would not 'be waiting to see if I am told' I would be asking first thing if they could explain the incident to you and what has happened since.

However, if I am reading correctly, you weren't in an area where the teacher was able to get to you. The teacher still has an obligation to make sure all other children leave their care safely, rather than track down a parent not in the immediate vicinity to them.

Whilst i agree things could've been handled better, I think you need to approach then.