I have had several like that; but as the buyers left me FB I realised that it is wrong; what happens is that at the PO they do not scan the item, they just get the buyer to sign for it.  That means it stays on the tracking site as 'awaiting collection" for ever.  I did keep checking on one item, just from interest, for several months. 

It also happened with the item that the buyer did chargeback on; in that case it did worry me; I contacted AP 2x and still have no explanation from them (fortunately that did not matter and I got my chargeback overturned).