This is not normal and not the way cats lose heat like dogs.
Cats pant when they are incredibly stressed or have asthma. Cat asthma is relatively common. They live with it quite merrily and is usually no cause for concern as long as you know and can keep an eye on it. It would be worth a quick trip to the vet just to make sure. If it is a bad case she may need treatment, probably not but it is always good to get these things checked out because if she did have a big attack at least the vet would already know what was wrong with her.