Since the discovery of the iron-pnictides superconductors most of the efforts has been devoted to the study of the fundamental questions concerning the coexistence of magnetism with superconductivity and the mixed phase. Nevertheless there are new phenomena that have risen in Cobalt and Rhodium-doped 122 single crystals: very recent 75As NMR measurements have evidenced that, in the normal phase, a slow dynamics is responsible for an activated behaviour of the spin-spin relaxation rate 1/T2. The physical origin of such a phenomenon is still debated, and we wish to study it by muSR, to compare and complete our NMR measurements, with another local probe technique. The understanding of such an effect may shed light on the comprehension of the normal phase of these systems, where new exotic types of order, like the nematic one, have been suggested.