I received a "Suspicious Account Access" notification from Facebook telling me that someone has logged into my account from a "computer, mobile device or other location you've never used before". When I logged into my account, Facebook showed me a page which claims my account was accessed from "10.158.15.35".
The 10.0.0.0/8 range is not publicly routed IP address space, it is reserved for local use, so this is not a case of someone trying to access my account over the public Internet.
Has anyone else seen anything similar? Does this mean that someone at Facebook is trying to break into my account, or is this some kind of bug in their system?