The oldest and fattest dragons become excessively jealous of their hoards, and appreciative of all the soft bubble wrap in modern parcels. It’s all the postal staff can manage to hook out a few parcels each time the dragon’s attention wanders.
Take solace, perhaps, that your delayed parcel is making a venerable dragon comfortable in their latter years.
Postal dragons like fresh parcels, and will generally permit them to be removed from the hoard once the springyness has been squashed out of them.