That's pretty unusual that Callie likes the vet so much.
You're very lucky that she does though and doesn't get stressed out.
I know my girls sure don't like the vet and start to shake on the way there. I swear they know the way to the vet by car and it's like 20 minutes on the highway from here. I think they hate getting poked and prodded. The last time I brought Shayla and Maggie in for their shots Shayla hid under the chair in the waiting room while our vet was examining Maggie. LOL