Do you expect your daycare/preschool directors to introduce new staff?

We just started at a brand new school last month (small Montessori daycare/preschool). We were never officially introduced to the teacher's assistants, but they have proven to be excellent, and our daughter loves them. This morning, another new assistant was there.

It's a state registered school, so I think everyone must be vetted? I just assumed we'd get an email or even a verbal, "Hey, here are our new helpers!" ... Is this expecting too much? Or, are staff turnovers or new people relatively ignored?