I'm curious about this, as I said in my comment above. Logically there shouldn't be any way that Google could have indexed them if they were secured behind a username and password. So I'm pretty sure that my friends-only postings were indexed back when they were public. Were any of yours public at any point in the past?
If somehow Google is getting at secured postings then that's a concern.
If somehow Google is getting at secured postings then that's a concern.