Are you sure about that? If "different" was supposed to modify "think", then yes, but isn't there are an admittedly more rare construct of verb predicate-adjective? Or would it have to be in quotes for that to be correct? For example, "Be different" (probably a bad example, since imperatives have an implied subject, I.E. "you", and in this case, "different" is modifying "you", but in "think different", "different" is not modifying "you").