Zheng et al. [Zheng, Gao, Ye, and Zhang, Phys. Rev. A 83, 061401(R) (2011)] have measured a strong linear pressure dependence of the nuclear relaxation rate of ${}^{3}$He in glass cells typically used to generate and/or store polarized ${}^{3}$He at room and cryogenic temperatures. Their interpretation is that this linear dependence is a general characteristic of paramagnetic wall relaxation, and they offer a theoretical explanation of the effect based on diffusion theory in the bulk with an incorrect boundary condition. We question the physical basis of the boundary condition and suggest some alternate explanations of the observations. Numerous previous studies support a broadly valid pressure-independent model for wall relaxation.