Gray got his first taste of competitive action this season when he stepped off the bench to replace Daryl Horgan at Ibrox on Sunday.
Hibs boss Paul Heckingbottom also gave Ryan Porteous and Oli Shaw further minutes at East Mains.
Goals from Shaw and Jamie Gullan had Hibs 2-0 up before Lewis Sawers pulled one back for the Pars. Gullan scored again for Hibs but Paul Brown made it 3-2 in the last minute.
Hibs: Cantley, Gray (Block 60), Sadiki, Porteous, Doig (Yeats 66), Campbell (Hodges 83), Stirling, Galantes (Bradley 83), I Murray (Woods 83), Gullan, Shaw (Fairley 60).