The coins in your SR account don't exist in the block chain. They are kept in a separate database that SR manages. When you submit a withdrawal, it can take a few hours to process. That's different from the bitcoin network / block chain, where a transaction shows up across the network within seconds. You submitted a withdrawal and a few hours later the coins showed up, so everything went as planned. Well, almost everything. Keep in mind that, although the SR interface allows you to translate bitcoins into American dollars for convenience, you don't have dollars in your account. You have bitcoins. So when you withdraw X amount, that's BTC, not USD.