Recent advances in diffusion weighted MRI have reignited interest in spherical (or isotropic) diffusion encoding. For such encoding to reach high efficiency (minimal echo time), the gradient waveforms have irregular shapes, by design. As such, they lack a well-defined diffusion time and can even be spectrally anisotropic. Most analysis methods based on such encoding assume that diffusion is multi-Gaussian, i.e., that the diffusion is not time-dependent. Since this is a central assumption, we investigate if spherical diffusion encoding is indeed rotation invariant, or if the diffusion time anisotropy has a discernible effect on the diffusion weighted signal in healthy brain.