The perovskite iridates Sr2IrO4 and Sr3Ir2O7 represent novel systems for exploring the electronic structure that is characteristic of Mott insulators upon carrier doping. Using angle-resolved photoemission spectroscopy (ARPES), we reveal a previously unobserved suppression of spectral weight near the Fermi level in the conduction band of very lightly electron-doped (Sr{1-x}Lax)(3)Ir2O7 followed by a loss of coherence at high temperature. The doping and temperature dependence of this suppression suggests a correspondence with the antiferromagnetic Mott state. These results connect (Sr{1-x}Lax)(3)Ir2O7 to other doped Mott insulators and add to the growing evidence of universal physics in these systems.