Well, I don't know that it is a Montessori practice, but that teacher sounds like no fun. And IMO preschool should be fun! Have you gone and observed the class?
I am by no means an expert on Montessori, but I will share my experience. I observed an elementary level one last spring and decided against it. I really liked the small class size, and that each student had an individual education plan, different weekly goals and they could choose the order in which they did the assigned activities. However, in the classroom all the students seemed to be doing their own things and not really interacting with one another. Even snack time was taken when they wanted so, for example, there was one girl sitting alone eating snack. While they were all busy learning, I didn't feel like there was much excitement in it.
For a quiet kid who enjoys doing things on their own, it would probably work great. But I could not imagine how my extroverted, funny, bubbly 7 yr old who is brimming with enthusiasm for learning new things would fit there.
I agree with Austin, go with your gut. And if you can, get in there and observe.
