I often order form China and sometimes Japan/Korea. Sometimes even when item is shipped with FedEx it takes a while to clear customs once it arrives in to US. I had instances where items were held for about a week and in one case almost 3 weeks once they reached US customs.
So far everything I ever ordered reached me sooner or later, so I would not be worried to much. With that said, since this is a high priced item I would make a "paper trail" of everything and contact DJI just in case something did happened and you need to go trough process of refund.