Gels of dibenzylidene sorbitol (DBS) in poly(propylene oxide) (PPO) show an increase in viscosity in a certain temperature range during melting. This so-called thermo-thickening behaviour is quite uncommon. In the few already known cases, the thermo-thickening is caused by simple thermodynamic processes that result in the formation of structures. We show for the first time that, in the case of PPO-DBS gels, experimental parameters like sample volume and heating rate play an important role and indicate non-equilibrium behaviour. It turns out that the peculiar thermo-thickening is the result of a reformation of the fibre network structure, which was destroyed earlier due to a strong temperature gradient within the sample.