And I am sure it has nothing to so with how she is behaving when the drop off occurs.
I worked in child care for years. Lots of kids would cry when mom would drop them off, but 5 minutes after she left they were fine. I had one boy who would cry when mom dropped him off, then cry when mom came to pick him up because he didn't want to leave my house. Kids sometimes cry during transition times, it is not necessarily indicitive of abuse, expecially at toddler age.
Now if a 13 year old were panicking, I would have concerns. But a 2 year old? That is par for the course.
