The behavior of the differential group delay (DGD)root-mean-square (rms) value is investigated for a buried G.652fiber line in a metropolitan fiber plant outside Stockholm, Sweden.This study presents measurement results from two different mea-surement periods where the same fiber and the same measurementequipment was used. In total,2800 hours of measurements wereperformed. As expected, the recorded DGD rms-value variedwith time. The measured standard deviation for the statistics ofthe DGD rms-value fits reasonably well with values presentedin literature. The fiber line, which showed a DGD rms-value of0.45 ps in average, had an extremely long time constant. Evenafter2800 hours of measurements we have not closed in on theexpected asymptotic distribution of the measured DGD rms-value