The observation of the P_{cs}(4459) by the LHCb collaboration adds a new member to the set of known hidden-charm pentaquarks, which includes the P_c(4312), P_c(4440) and P_c(4457). The P_{cs}(4459) is expected to have the light-quark content of a Lambda baryon (I=0, S=-1), but its spin is unknown. Its closeness to the {bar{D}}^* Xi _c threshold – 4478,{mathrm{MeV}} in the isospin-symmetric limit – suggests the molecular hypothesis as a plausible explanation for the P_{cs}(4459). While in the absence of coupled-channel dynamics heavy-quark spin symmetry predicts the two spin-states of the {bar{D}}^* Xi _c to be degenerate, power counting arguments indicate that the coupling with the nearby {bar{D}} Xi _c' and {bar{D}} Xi _c^* channels might be a leading order effect. This generates a hyperfine splitting in which the J=tfrac{3}{2}{bar{D}}^* Xi _c pentaquark will be lighter than the J=tfrac{1}{2} configuration, which we estimate to be of the order of 5-15,{mathrm{MeV}}. We also point out an accidental symmetry between the P_{cs}(4459) and P_c(4440/4457) potentials. Finally, we argue that the spectroscopy and the J/psi Lambda decays of the P_{cs}(4459) might suggest a marginal preference for J = tfrac{3}{2} over J = tfrac{1}{2}.