Atomic transitions produce photons. You can create beams of photons with a laser. In lasers rays of light are produced. Will rays of gravitons (or small directed gravitational waves) be produced also?
If you're transitioning between the two orbital states, the quadrupole moment of the atom definitely changes, and the gravitational potential energy of the system definitely changes. Unless the new complete quantum theory has some novel way of suppressing gravitational radiation, the system should definitely radiate some gravitational waves, and if the final theory's radiation profile is expressible in some sort of "graviton" basis, it will "radiate at least one graviton"
Of course, all of the caveats about how vanishingly undetectable all of this is would still apply, though, and note how speculative the above paragraph was.