Gibson was placed on waivers by the Capitals for the purpose of reassignment to AHL Hershey on Friday.
Gibson hasn't yet made his NHL debut, and he's slated to begin the regular season in the minors if he clears waivers. He made 23 regular-season appearances with Hershey last year and went 9-9-5 with a 2.94 GAA and .903 save percentage.