I just put up my first item for sale on eBay, and the buyer has just paid me via PayPal. He's in Shanghai, China (I'm in the US), and PayPal included this warning when he paid me: "Important note: [the buyer] has provided an unconfirmed address. Please check the Transaction Details page for this payment to find out whether you will be covered by PayPal Seller Protection." Is this a common situation? Should it worry me? I assume everything will be fine, but I've always wondered why so many people refuse to sell worldwide. What could go wrong?