My sugar glider, Vita, never did that. But if I were you I would locate a vet and take him there as soon as posible. Or call a local vet to see if its a normal noise for a sugar glider to make. Alot of people say its a happy noise but you can never be to sure. People say cats purr when they are happy but truthfully, due to scientific reasearch, cats purr when they have any sort of human interaction. This could be something like that. But like I said to be on the safe side I would ask a vet about it. Hope that helps. And I hope your little buddy will be ok.