Google Docs has sent a notice to a number of users notifying about a recent issue with Google Docs account.
We’ve identified and fixed a bug which may have caused you to share some of your documents without your knowledge. This inadvertent sharing was limited to people with whom you, or a collaborator with sharing rights, had previously shared a document. The issue only occurred if you, or a collaborator with sharing rights, selected multiple documents and presentations from the documents list and changed the sharing permissions. This issue affected documents and presentations, but not spreadsheets.
As part of the fix, we used an automated process to remove collaborators and viewers from the documents that we identified as having been affected. We then emailed the document owners to point them to their affected documents in case they need to re-share them.