Wish List is designed to save your surprises. If you prefer, though, you can always find out what's been purchased from your Wish List by selecting Purchased or View All from the Show drop-down menu at the top of your Wish List.
To change your Purchased Item filter settings:
Note: You can apply this setting to each list with the drop-down menu at the top of the page.
Note: The Purchased Item filter and warnings only appear when you're logged in to your account. Your Wish List might reveal a surprise if you don't sign in to the account you used to set up the Wish List.