I have mine on all the time, they must have well over 1000 if not nearly 2000 hours running time now (53k miles).
Strictly the bulbs are wear items like a normal halogen bulb but depends on dealer if they will replace them, if the car is quite young and you had issues before then your chances are probably good at dealership you bought it from.
PS: I was asking which version of the xenon lights you got.... there are 3 revisions, they are all slightly different in how you change the xenon lamps.