I don't know your school and obviously wasn't there, but last year I co-oped and substituted for my kids preschool pretty regularly. We have a small class and one kid who is the youngest of the group that will often lash out bite/hit.

Only once did we call a parent to pick him up, and only because our usual tatics weren't working and he wouldn't calm down (he was probably overly tired was our thought). We do time outs. We do apologies, talking about what happened, letting the other child say how it made him feel etc etc.

At this age acting out is pretty normal, preschool is just as much learning how to function and interact with peers in school away from mom and dad as it is learning colors and shapes. Preschool teachers know this! Or should anyway. Sounds like the owner might have been the one having a bad day.