Hi Vevalee,
My daughter use to do the exact same thing, but the teacher always told me that as soon as I walked out the door after dropping her off she was ok. She'd also be happy and excited when we picked her up and always told me she had a great day! It's completely normal and you can be sure that you're daughter is OK. We've all got to do things that are difficult sometimes, like being a working mom and feeling a little guilty about leaving our children BUT remember that children are very resilient and, being in preschool will make her a healthier and more well-rounded individual. Keep up the great work!