If the tissue was suitable for transplantation, it has to still be living. Which means they got it off the corpse after the patient had clinically "died", but before complete degradation of all tissue had set in. They chill the parts for transport, like they do in cases of heart transplants. If the part is capable of being used for transplantation, I'd say it has a good chance that, if the patient was HIV positive, the specimen has a chance of infecting the host. Perhaps a very miniscule one, but if they could guarantee that it was no risk at all, they would probably not be recalling body parts.