This would give a clue as to how much (or if) the contrast was stretched to make those particular two spots stand out. I doubt the smaller feature is an image artifact, but I hesitate to make any "remote sensing expert" pronouncements. This mission has already made a liar out of me several times over. At any rate, forgive me if I think out loud some more.

If the planetoid surface was sooty black, and the substrate a lighter, but still a dark gray (like old asphalt, or sediment-laden ices), the image could still be processed to make them look that bright. I wouldn't worry about angles of incidence, this is not specular reflection, or it would not remain so consistently bright until just before it went into shadow beyond the terminator. Its just a patch of lighter gray than its surroundings, and it may not be all that much lighter. The interesting thing about it is how its only in that crater, and only on the tip of the central peak. Maybe this is a new feature, the result of a relatively recent impact, and the sub-surface material has not had a chance to darken up yet.

Asteroids are particularly interesting because they are accretion bodies. They are made up of an accumulation of objects that struck them. But accreting planetesimals either adhere, (perhaps after knocking off some debris), or tend to break the body apart altogether. These two processes work simultaneously, but against each other, probably influenced by the interplay of a variety of local conditions. Which gets the upper hand in the long run determines whether you get a planet or nothing at all. Like everything else in nature, its a totally random process gently guided by subtle external forces. Unexpected resonances appear in unpredictable places and times.

Are the asteroids there because that is a part of the solar system were conditions did not favor either planet building or sweeping the orbit clean, but something in between? As the largest asteroid, and one old enough to be gravitationaly spheroidal, Ceres might hold some clues as to the chemical and dynamical history of the early solar system. Crater statistics (relative sizes and number of overlaps)could give us a lot of clues as to the early environment of the primordial solar nebula.

As an aside, a lot of these rocky bodies are quite dark. For example, the full moon looks blinding yellow-white against a dark sky, but it is made of very dark material. Take a camera with a light meter and get a reading of the brightness of a black asphalt road at noon. Use that shutter speed and aperture and take a photo of the night moon and it will come out perfectly exposed. The sky and stars behind it, of course, will be pitch black. Its the same trick a photographer will use to photograph a face in the shade on a bright, sunlit beach. Get in close, get a meter reading on the shadowed face, then step back and take your shot. The sand and sky will be over-exposed, but the face will be perfectly recognizable.