Ilford MG FB versus Ilford MG FB IV

I obtained a few boxes with Ilford MG FB paper (no I, II or III or anything), carton thick, the label under the Ilford name is light green.

This paper has (compaired to Ilford MG FB IV) a off-white towards a hint of yellow base colour. Is this due to old age (the paper itself prints fine) or was this paper always with a off-white paper base?

thanks & best,

Cor

The box of MG FB glossy that i have is white, not off white.