True they're not uniform, but CO2 is well mixed in the atmosphere. The daily or weekly values may be a bit too fine grained in resolution, but the monthly average is better for giving the trend.
I would expect that if Mauna Loa is downwind from a CO2 outgassing, that it will remain with higher levels until the CO2 spurt has finished, or at least until the prevailing winds drop (thanks El Nino).
As with all of these things, it's easy to get too focused on single data points, and the human nature of liking nice round numbers. The trend is up, and appears to be increasing, but you can only ever see the real detail in the rear view mirror.