We report the results of measurements of the proton ${(}^{1}$H) spin-lattice relaxation rate ${\mathit{R}}_{1}$ at high temperatures (to \ensuremath{\sim}1400 K) in the hcp (\ensuremath{\alpha}) solid-solution phases of the Sc-H, Y-H, and Lu-H systems, and of ${\mathit{R}}_{1}$${(}^{45}$Sc) in Sc-H and Sc-D solid solutions. The latter measurements show unambiguous evidence of an anomalous increase at \ensuremath{\sim}1000 K, whereas ${\mathit{R}}_{1}$${(}^{1}$H) shows no such increase at any temperature. This behavior of ${\mathit{R}}_{1}$${(}^{1}$H) contrasts with that in the bcc V-H, etc., solid solutions where anomalous relaxation occurs below \ensuremath{\sim}1000 K, and in all investigated metal dihydride phases, M${\mathrm{H}}_{2\mathrm{\ensuremath{-}}\mathit{x}}$. The anomalous ${\mathit{R}}_{1}$${(}^{1}$H) behavior in \ensuremath{\alpha}-${\mathrm{VH}}_{\mathit{x}}$, \ensuremath{\alpha}-${\mathrm{NbH}}_{\mathit{x}}$, etc., may be understood in terms of fast spin relaxation in the ${\mathrm{H}}_{2}$ gas in equilibrium with the solid, mediated by fast gas-solid exchange of hydrogen. However, in the present systems, \ensuremath{\alpha}-${\mathrm{ScH}}_{\mathit{x}}$, \ensuremath{\alpha}-${\mathrm{YH}}_{\mathit{x}}$, etc., the ${\mathrm{H}}_{2}$ gas pressure in equilibrium with the hcp systems is extremely low, resulting in negligible ${\mathrm{H}}_{2}$ concentration in the gas phase, and consequently a negligible contribution to ${\mathit{R}}_{1}$${(}^{1}$H). In contrast, some of the present measurements indicate that the ${\mathit{R}}_{1}$${(}^{45}$Sc) anomaly does result from the hydrogen content of the metal, but the mechanism remains unexplained.