For a few weeks now I have noticed that if I leave an Edit Post page open for a while, when I return to it there is a dashboard display at the top. The first couple of times I thought I'd somehow navigated to the Dashboard, but then I happened to scroll down far enough to realize that it was displaying at the top of the Edit Page. It's even happened while I was typing a new post--darned thing just suddenly appeared.
A few days ago I opened an Edit Page and left it. When I looked at it this morning there were no less than five Dashboard displays, one above the other. I suspect it happens whenever the Dashboard updates. I've turned off the Development blog and WordPress News to see if the problem goes away, but I am trying to figure out why this started to happen, and how it can be controlled. This doesn't seem to me to be normal behaviour.