Is there any nasal or eye discharge? Any diarrhea? If you see any of that, I'd get her back to the vet asap, but it might be that she's just got a touch of kennel cough. As long as she's eating well, drinking water, eliminating normally and is energetic, I wouldn't worry too much, but given her age, I'd probably be setting up an appointment for sometime this week--earlier if she gets worse. If she gets better in the meanwhile, you can always cancel the appt.