All Nikon Australia stock is supplied by Nikon Asia which are based in Hong Kong.
If the warranty card says Nikon Australia it is one that has been supplied to Nikon Australia from Nikon Hong Kong and then on to a local retailer.
Stop panicking Steve.
Updated,
just had a look at a box and it has D800 (HK) on the main sticker on the end of the box and HK on the accessory box.