You know, I think it's odd, too. But I chalked it up to general TR-oddity; that episode frustrated me because it seemed to waste most of its opportunity for character revelations.
But Giles does, at some point in S4, say to Spike that maybe Spike was chipped for a higher purpose, maybe he needs to rethink his life ... and Spike laughs at him. I can't remember which episode, unfortunately. I think it must be post-"A New Man," and the scene is Giles paying Spike for his assistance in that episode.
Re: I miss Tara, too
But Giles does, at some point in S4, say to Spike that maybe Spike was chipped for a higher purpose, maybe he needs to rethink his life ... and Spike laughs at him. I can't remember which episode, unfortunately. I think it must be post-"A New Man," and the scene is Giles paying Spike for his assistance in that episode.