I would guess not, but if one just falls out (probably while driving) shouldn't it be covered as a manufacturers defect? I know they are only $15-$20 but it really pisses me off that it pops out that easily.
One thing I have found with the X3 is that quality is lacking compared to my new 335i
I guess they have to cut costs somewhere to make a larger vehicle with the same options/features as the 3 series the same price or less...
Other thing I noticed is the door seals are wearing like crazy, brown/tan spots all over them after 24,000 miles. comparing them to the 3 series they just feel cheaper (3 series has no sign of wear on them).