If a case has not been opened I would NOT contact the buyer... they could be opportunistic in claiming INR when they probably have the item. AP is not reliable in providing delivery scans.

In my experience, unless your buyer is particularly special, no one tends to check the tracking once their item has been delivered. So go ahead and open a customer enquiry 'where's my parcel?'. If it really has been lost and the buyer opens a case, at least you're a few days ahead and bring proactive.