A Focused Plenoptic Camera in Galilean configuration is studied and its aberrations behavior is interpreted with the Nodal Aberration Theory (NAT). Sequential ray tracing is applied to individual optical channels constituted by the camera objective and individual decentered microlenses. The wavefront aberration field is retrieved at the exit pupil of the optical channels and is analyzed through the Zernike Fringe decomposition technique. Decentered optical channels show nodes in the field-dependence of different Zernike coefficients approximating the wavefront aberration field. The nodal behavior is a consequence of the loss of rotational symmetry in a decentered optical channel due to the displacement of a microlens with respect to the mechanical axis of the camera.