During internal conversion, coherent superposition of different electronic states is formed. This superposition is not on a position basis but on the energy eigenstates. However, immediately after it is formed, the fractions of the nuclear wave packet on each electronic state follow different paths on the potential energy surfaces till their overlap is null, causing electronic decoherence and still selecting the energy eigenstates as pointer states. Thus, although the system's superposition is initially in the electronic energy eigenstates (not particularly sensitive to gravitationally induced collapse), the nuclear wave function is driven to a superposition of different positions, which in turn has a non-null gravitational selfenergy and may collapse.