As if you didn't have enough things to worry about, check out Michael Horowitz's article at Computerworld:
Google knows nearly every Wi-Fi password in the world
If an Android device (phone or tablet) has ever logged on to a particular Wi-Fi network, then Google probably knows the Wi-Fi password. Considering how many Android devices there are, it is likely that Google can access most Wi-Fi passwords worldwide.
Oh, and change your wifi passwords now. You'll be completely safe until the next device logs in...