We reinvestigated the 2 + 1 REMPI Q-branch spectrum of the a ''(1)Sigma(+)(g) + X-1 Sigma(+)(g) system of N-2 at around 202 nm in a Doppler-free configuration with counterpropagating laser beams. Highly accurate absolute calibrations were performed using either an 12 reference standard or a frequency comb reference laser. The observed rotational series shows a clear effect of a perturbation in terms of an anticrossing located at J = 26. In addition to the improved set of molecular constants for the a ''(1)Sigma(+)(g) state, we tentatively assign the perturber state to be the (1)Sigma(+)(g) (II) state of N-2.