As I understand it, it is not unusual to have some. The significance is if there is a discrepancy between the number in the CSF and the number from blood.
If the two results are identical, it indicates you are unlikely to have any inflammatory disease specific to the central nervous system (of which the most common would be MS), and may not have any disease at all.
But if there is more banding in the CSF test than in the blood test, it would indicate there is an inflammatory process going on in the CNS that is not true of the body in general.
So the result is pretty meaningless unless they have compared the two tests side-by-side. As long as they match, it is probably not significant.