With the aid of residue evaluation, the time-dependent reflection response Ggr(t) of Shinkawa et al., which was recently used in a coupled-core stability analysis, is verified. The expansion series of the Ggr(t) is summed with the Watson method, and its consistency with neutron conservation is checked. The result justifies the previous addition of −δ(t) to a reflection term, which was made in the stability analysis. The meaning of the response flux eigenfunction expansion for a moderator region is discussed.