Weird squeeling?

[xFluffyHamsterx]

So i've had my hamster for a year now, hes settled and tame. I've recently gave him a sand bath, however today during the day i heard him squeel - it wasnt loud and didnt sound alarming. Hes done it twice since earlier and I can't think why - i wasnt near the cage and he was sleeping and the second&third time i was in the same room but wasnt near him. He isnt afraid and doesnt seem in pain - does anyone know what this can be? We have a hamster in another room to add

Its hard to explain but its more of a high pitched grunt, or sounds like their stomach is rumbling/or burping but sounds more like a grunt