If my character moves from a square within the area of
a grease spell to an adjacent square outside the spell’s area,
does he have to make a Balance check?
No. As a general rule, terrain effects apply only to
characters entering a square with the terrain effect, not to those
leaving such a square. A creature leaving a greased square need
not succeed on a Balance check to do so (of course, he must
have succeeded on a Reflex save to remain standing