Header field not saving Input Format

While creating or editing a view, the Header content doesn't seem to be saving the input format, For example, I put some php into the Header field to add a drop-down selector to a certain view, selecting php code as the input format. Instead of rendering the drop-down selector, the php code is displayed as text in the Header area. When I go in to edit the view I notice that filtered html is the selected input format, despite my having selected php before I saved.

Is this a bug or am I doing something wrong?