I’ve had this issue for a very long time through multiple installs and projects. I’ve tried searching to no avail and I’ve managed to work around it but it’s finally irritated me to almost certain death…
I’m running the latest version of ADT on Eclipse 3.7.2 on Windows 7 x64 with Oracle JDK 1.7.0_05
What happens is that after editing a layout in the graphical WYSIWYG-ish editor and setting a TextView to some text, when I switch to the text/XML view I have the following happen:

As you can see, there’s the closing tag for LinearLayout at the bottom without a line number. For some reason, the text editor offsets all visible text by one line. If I highlight it, it corrects itself sometimes and only partially:

Is anyone else having this issue? I can’t be the only one. Thanks
Edit: Tried Eclipse 4.2, same issue.

I most definitely have this issue, after making changes in the graphical editor too.
I’ve found that if you select all, delete with a backspace then undo, it resolves itself. It happens so much I have the shortcuts down to nothing more than an inconvenience now
Edit: Ok, so the problem is Eclipse 3.7. Updating to 4.2 has fixed this for me.It appears not. For me, the glitch seems to occur only when changing an attribute of a view using the WYSIWYG editor