We report on the spontaneous polarization transfer from dynamically hyperpolarized H-1 to C-13 during magic-angle spinning dynamic nuclear polarization (DNP) at temperatures around 100 K. The transfer is mediated by H-1-C-13 cross-relaxation within methyl groups due to reorientation dynamics, and results in an inverted C-13 NMR signal of enhanced amplitude. Further spreading of transferred polarization can then occur via C-13-C-13 spin diffusion. The resulting process is equal to the nuclear Overhauser effect (NOE) where typically continuous saturation of H-1 by radio frequency irradiation is employed. Here, hyperpolarization by irradiation with microwaves in the presence of typical bis-nitroxide polarizing agents is utilized for steady-state displacement of H-1 polarization from thermal equilibrium and perpetual spin-lattice relaxation. An effective BC enhancement factor of up to -15 has been measured. Presence of Gd(III) furthermore amplifies the effect likely by accelerated relaxation of H-1. We provide experimental evidence for the proposed mechanism and show that DNP-induced cross-relaxation is a robust feature within proteins and single amino acids and discuss potential applications.