Sorption and diffusion of dichloromethane vapor in amorphous poly(ethylene terephthalate) (PET) were investigated, with the aim of studying how aging phenomena, at different temperatures, influence the transport properties. It has been found that aging produces the appearance of non-Fickian behavior in the sorption curves as well as the reduction of the diffusion coefficients. Furthermore, aging at 60 degrees C reduces the sorption of vapor at low activity, and this led to the hypothesis of the presence of ordered domains in the aged samples. In this case, the process of solvent-induced crystallization is favored, and it appears at lower activity.