Michael Horowitz, author of Computer World's blog "Defensive Computing," has an interesting article called "Google knows nearly every Wi-Fi password in the world." If true, it wouldn't take much for the NSA or some other law enforcement division to get your Wi-Fi password and have access to your computer without a warrant.
There's a feature in Android where you automatically backup all your passwords, including your Wi-Fi access points to the Google Servers. It is possible to disable this. Google isn't the only one, though, and that's why it's never been more important that we have oversight of our government. Nobody seems to want to press that, especially in congress.