To reproduce.... Try edit a post that's a little way down the page.When the edit overlay shows just click inside the editor and the page then scrolls to top. You need to scroll all the way down again to the overlay
Oops, looks like our workaround stopped working with a few other changes. I've re-added it and it seems to be working in my tests. (It basically detects this case and scrolls you back down to the editor.)
Though I do want to note that this seems to be an Android browser bug.