I would probably see if he could change it out if you have the extra tile.

If he hasn't grouted yet, I would ask him to replace it.

As others said, if it hasn't been grouted yet and there is an extra piece of tile, it doesn't hurt to ask if the tile guy can replace it. I personally don't think it's the end of the world to have a chipped corner, since few (besides yourself) will notice. However, since it's your home and you've noticed it, I see no reason not to try to have the chipped tile replaced.

This happened in ours. The chipped one is somewhere under the left sconce cutout (if you blow the pix up you could probably see it). I noticed it right away. But it's a kids bath so I didn't say anything. I feel he would have done perhaps some damage to others if he tried to take it out.