Needing to adjust for higher monitor brightness prematurely?

Purchased a NEC MultiSync 2490WUXi2-BK 24 nearly one year ago. In order to keep my brightness at about 95cdm, I am finding a need to raise my brightness over the past few calibrations from 70% to 74% to 77%. I left my contrast the same at 47%.

Do you think that I may have a problem?

Much appreciated,

Mike