Precise measurements of the dissipation and resonant frequency of a torsion pendulum reveal an anomaly in the inferred viscosity and normal density of liquid 3He near the superfluid transition. We present an argument that the anomaly originates in the large viscosity and large viscosity change of the normal component in the torsion tube in the vicinity of the superfluid transition. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.