What does this tracking mean?

[bnew0112]

I bought something from America, (I live in Australia) and the latest tracking message said: 'Arrival at unit' which was still in America somewhere in Kentucky and still hasn't reached Australia. When I checked the usps tracking site it said arrived at post office which also said it was still in America and the estimated delivery date was Saturday 13th may? Or the 14th in terms with the us time zone. I'm a little concerned because I've heard that this tracking message is supposed to indicate that the item has arrived at the destination post code where it will be out for delivery which would obviously not be right in this case. So my question is did usps or the seller have the wrong address and didn't know they were supposed to send it to Australia? I checked the eBay shipping method and it was indeed priority international shipping.