I agree with Reinz. Your first responsibility is to the reptile to make sure he is healthy and not harboring a early RI or even a virus. Next , the customer absolutely needs to know that the animal is symptomatic with a potential RI. They have already committed to a payment plan and have a right to get out of the deal or not. But you have to be willing to inform the customer of the issue. Maybe they will want to purchase a different animal either way they need to know. Just be straightforward and you will keep the respect and trust of the customer. Good luck.