Normally, when you transform (i.e., move, scale, rotate, or skew, see Chapter 6) an object that uses gradient on fill or stroke, the gradient handles are transformed along with the object, so the gradient stays firmly put in place. However, the third Affect button on the Selector tool controls bar (6.10 What Transformations Affect) can change that.
If you uncheck this button (checked by default), gradients will remain fixed relative to the canvas, no matter how you transform the objects that use them. This can be useful, for example, if you want to scale an object up or down so its size matches that of the elliptic gradient it uses.