As smoto5 says, it could be cracks in the coating,
but looking at photo 1, it looks to me like the metal is cracked, if you look closely at the greyish "crack" at the base of the spoke you can see a fine dark line in the centre of the greyish area, this looks like a crack to me, the greyish bit is the metal under the coating and the coating is chipped off along either side of the crack, as the wheel flexes through torque and load stress's the metal either side of the crack will move, and as the two edges of the crack move independently of one another the coating along those edges gets chipped off exposing the crack in the centre.
Having said all that if you can't tell if it's cracked or not visualy, then you need to get it tested, there are various techniques that would determin if the metal is cracked or not.
Not sure how much heat is applied to the wheel during the coating procedure, but If there were minute cracks in the original wheel, application of enough heat would definitely "open them up" make them larger and more noticeable.
it's worth noting too that by heating any metal above certain temperatures will change the properties of the material, which can lead to localised hardening and embrittlement, causing cracks, or even softening and weakening. the same applies to cooling after heating too.