Exactly, it raises the possibility. And by raising the possibility it says something about the nature of this "feeling of free will" that it is not identical to free will. In the case of "the feeling of pain" it is - in a stronger sense - identical to pain.
Note that I move away from this picture when I say that it is consciousness as a whole that is free, because even a feeling of free will is only a small part within our conscious awareness.
Exactly and the "feeling" itself may be illusory much like the sense of proprioception (position) which can be interfered with using electromagnetic induction.