There is an issue when changing the angle of a linear gradient. Although the gradient display in the Controls window updates immediately with the new angle, the Composite display does not update until a new angle value is entered. Basically, the composite window display is always one step behind the Controls window display. See the attached video.
EDIT:- Discovered that it’s not a bug, simply not intuitive. After changing the value, you have to update it in the Composite display by either pressing Return, or clicking off the angle control. As I said, not very intuitive. I’ll have to include that little nugget in my tutorial.