The recent interest in carbon-based materials like graphene stimulated a deeper analysis of the magnetism in graphite defects. In a previous µSR experiment we observed an unexpected muon depolarization in ball-milled and exfoliated graphite which may be ascribed either to a Korringa-like mechanism due to an increased carrier density induced by the high defect concentration (a model similar to the one suggested by S. F. J. Cox and co-workers for HOPG), or to depolarization from dangling bonds at zig-zag graphite edges (non-negligible in crystallites with size ~ 6 nm and according to ad hoc calculations). A continuation of the µSR experiment at temperatures lower than 1.4 K (sorption cryostat) and in the TF configuration of MuSR spectrometer will give valuable information on the origin, the magnitude and the dynamics of the muon depolarization in these systems.