Since you've never experienced parasites before, and you're not sure, my recommendation would be to take them back to the vet and have the vet confirm or dispel your suspicions.
Mites are usually microscopic, so they are very hard to diagnose. If she starts to get scabs, then I would be really concerned. For now, I might just keep an eye on her to see if she scratches more. It could be nothing... sometimes my rats have a day or a few hours where they scratch and scratch, but nothing is wrong -- they just want to scratch!
