The only thing could have worried me is the battery. A refurbished unit has a new battery, while an used one could have several cycles on it. BTW his unit was less than two months old (according to your narrative) so it shouldn’t have more than 30 cycles on the battery. Did you check?
As I said, I am not even concerned about it, I haven’t had any issues with a replacement device in the past and the device is functioning perfectly.