No, in fact you've done something "horribly right" in parenting! Obviously, your DD feels safest with mommy and is able to express her emotions and know that even if she is freaking out, mommy is the one who will always be there for her.
My DH asked me once (when we were both picking up DD at preschool) why she is fine and then completely breaks down when we walk through the door. I explained that she is not necessarily sad, she is just emotional. As Marisa said, there is a great deal of mixed emotion when mommy appears - relief, anger, joy, self-pity, etc. and it just comes rolling out.
The good news is that this is usually just a phase and will pass. She won't freak out forever!
Maddy Moo - 2.5