I ran into this today as well, and I'm the only one that opens it for editing, and it said was open by 'currentuser'. Even after closing browser, let it sit for an hour, no go. Eventually I came back to it, and it was in Edit mode. Also, I did notice that later on, when I went in, and got the same thing, it gives a notification in the normal notification area that I could override, and there was an override button, and that seems to have worked.
We also use a dev version, that we then save as over the live version (have to use Replace feature), and it automatically pops up to publish the new version on the live. Well, couple tries, wouldn't work (just prompts for Replace, and nothing after that), left for meeting. Came back, tried again, it apparently replaced, asked to publish.. and then it couldn't because, guess what... Open for editing by 'currentuser'. Sigh. Open live version, override editing, publish, done.
