Experimental findings and rheological modelling of chemically treated single-wall carbon nanotubes suspended in an epoxy resin were addressed in a recent publication (Ma et al., J Rheol 53:547-573, 2009). The shear-thinning behaviour was successfully modelled by a Fokker-Planck-based orientation model. However, the proposed model failed to describe linear viscoelasticity using a single mode as well as the relaxation after applying a finite step strain. Both experiments revealed a power-law behaviour for the storage and relaxation moduli. In this paper, we show that a single-mode fractional diffusion model is able to predict these experimental observations.