Twitter Search Shows Updates from My Private Account!

Protecting Your Account Is Not Retroactive

When you protect your account, all tweets posted after protection will be private: unlisted in Twitter search and 3rd party applications. All tweets posted before protection, however, will still be listed in search engines and 3rd party applications. To find out how to remove your updates from Google search, check out this article. Twitter does not have the ability to remove content on other websites other than Twitter.com.
When you protect your account, only approved followers can read your updates.

What If My Account Has Never Been Public?

If your account has never been public, or in other words, has always been protected, your updates should never show up in Twitter search or other public search engines. If this is happening, change your password immediately and submit a request and include the following information:

• when this started happening
• where you've seen your private updates posted
• list any/all third party applications you use