Auto generating texture using a plane

I am auto generating the texture using GL_OBJECT_PLANE and it displays correctly on the polygon until I move the polygon upward. The texture follows the polygon.

Why does the texture follow the polygon when the plane is not moving? I thought that was how GL_OBJECT_PLANE was supposed to work.

Plane in 3D space can be defined by 4 values: normal and distance from origin.
If you translate your poly its distance from origin (0,0,0) probably changes -> its plane changes too.