It has been shown that hybrid inflation may end with the formation of non-topological solitons of the inflaton field. As a first step towards a fully realistic picture of the post-inflation era and reheating in supersymmetric hybrid inflation models, we study the classical scalar field equations of a supersymmetric hybrid inflation model using a semianalytical ansatz for the spatial dependence of the fields. Using the minimal D-term inflation model as an example, the inflaton field is evolved using the full 1-loop effective potential from the slow-rolling era to the U(1)FI symmetry-breaking phase transition. Spatial perturbations of the inflaton corresponding to quantum fluctuations are introduced for the case where there is spatially coherent U(1)FI symmetry breaking. The maximal growth of the dominant perturbation is found to depend only on the ratio of superpotential coupling λ to the gauge coupling g. The inflaton condensate fragments to non-topological solitons for λ/g≳0.09. The possible consequences of nontopological soliton formation in fully realistic supersymmetric hybrid inflation models are discussed.