I want to understand the following effect better (In Mathematica 9) .. Or, maybe, is it a bug?
Running the following line
FullForm[Subscript[α,β_]] gives as output,
(*Output*) Subscript[\[Alpha], Pattern[\[Beta], Blank[]]] But then, when I try to edit the above output, I get some unexpected stuff:

There is some strange spacing at the end, and the front end disagrees with the syntax (as evidenced by the red carat).
How do I understand what's going here?
