School Drop Off

My 4 year old daughter started school last week and it's her first time being away from family. She's only doing half days and seems to be having an ok time once things get going but she is having full blown meltdowns at drop off. Screaming, crying, hitting, using anything she can think of to delay. She's a smart kid so some of her tactics aren't as obvious right away. This is a really good school and I wouldn't be able to leave her there at all if I wasn't fully confident in it and her teachers but this is breaking my heart. Do all kids adjust or are some kids just defeated after awhile? I feel like this is going to have an impact on our relationship and I could really use some guidance if anyone had a strong willed child go through something like this. Does this sound like more going on mentally than most children and I should look into therapy or just an only child's response to not being with her Mom? Any reasources welcome. We're thinking of starting a gratitude journal for the family tonight to shift her mindset into a more positive place, has this worked for anyone?