I just bought some xm 10k's and they also have a black area around the base. This is the first time I have ever looked at a new halide bulb in person, so I am sure that they should be new bulbs. At $45 that is a steal! My lfs sells them for $129, and they are usually $89 online
i am pretty sure all manufacturers test fire their bulbs before shipping them out. you will also see some burn marks inside the center bulb. this is all normal. it is really hard to tell sometimes how old the bulb really is.