I was having problems with a rear V-brake for a while, being unable to keep it properly centered. I just discovered that it was mainly due to the cable housing connected to it being way too long. The housing was therefore pushing the brake to one side, making the normal centering adjustments not very effective. I cut about 2 cm of housing off, and it now works a whole lot better. To check for this, undo the quick release, and let the housing settle where it wants to. If this is nowhere near where it needs to be when connected to the brake, then it might be useful to change the length.

I've actually had this bike for several years, and have had all sorts of odd problems that were all caused by shoddy manufacturing and assembly. All the parts were decent stuff (Deore and above) and I got it for a good price, but I'll never trust Norco or the shop I bought it from to build another bike for me. Problems have included the water bottle cage mounts not being properly attached to the frame (they soon came loose and rattled around in the frame holes until I got it fixed under warranty). The headset was not properly adjusted from the start (which took me several rides to realize, by which time the bearings had started to make divots in the race, which caused indexed steering), many bolts were not sufficiently tightened and came loose on my first ride, and now I find that some of the cable housing was the wrong length. I'm glad that I now know a lot more about bikes and can build them myself.