After 6500 hours default color temperature drifted somewhat to lower values. It means it looks "warmer" than neutral 6500K. So 6500K after 6500 hours does not look like 6500K.
That can be a problem for a regular monitor, but not for the NEC 2490UXi.
For uncalibrated use: manual color temperature control with 100K steps is at your service.
For calibrated use: it has never been a problem. SpectraView calibration kit takes care of that.