lights&materials question

Hello all, I'm trying to use lights and materials in opengl. here is the code for the initialization:

        glShadeModel(GL_SMOOTH);						
	glClearColor(0.0f, 0.0f, 0.0f, 0.5f);	
        glClearDepth(1.0f);
        glEnable(GL_DEPTH_TEST);
	glDepthFunc(GL_LEQUAL);							
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
	float dif[]={1.0f,1.0f,1.0f,1.0f};
	float amb[]={0.5f,0.5f,0.5f,1.0f};
	glEnable(GL_LIGHTING);
	glLightfv(GL_LIGHT0,GL_POSITION,lpos);
	glLightfv(GL_LIGHT0,GL_AMBIENT,amb);
	glLightfv(GL_LIGHT0,GL_DIFFUSE,dif);
	glEnable(GL_LIGHT0);

and for the scene:

        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glLoadIdentity();
	glLightfv(GL_LIGHT0,GL_POSITION,lpos);
	glTranslatef(0.0f,0.0f,-6.0f);
	float dif[]={1.0f,0.0f,0.0f};
	glMaterialfv(GL_FRONT,GL_DIFFUSE,dif);
	GLUquadric *q=gluNewQuadric();
	gluQuadricNormals(q,GL_SMOOTH);
	gluSphere(q,1.0f,64,64);
	glDisable(GL_LIGHTING);
	glTranslatef(lpos[0],lpos[1],lpos[2]);
	glColor3f(1.0f,1.0f,0.0f);
	gluSphere(q,0.1f,8,8);
	glEnable(GL_LIGHTING);

when I position the light inside the sphere,the outer faces get colored.Is that normal or if it's not,could anyone tell me what's wrong? Thanks for any advice