The degree of clustering in 4D (ra, dec + 2 observables), increases with respect to 2D (when considering the same 2 observables). This is likely a consequence of the known ‘gridding pattern on the sky’ seen, e.g., towards the LMC. However this systematic does not dominate over the intrinsic distribution of statistical errors in the observables, since for example the clustering for the brightest sample (which has the smallest errors on average) is always larger than for any other subsample.