Why is my sugar glider mean?

this is my first sugar glider i have had, may i add the first sugar glider ive seen, i have had it for about 5 day's now and ever time i try to open the cage he is ready to bite!, i have a male sugar glider, and i am afraid of getting bit!, i have read many of thing's stateing that they are able/will bite, and i hate that god awful noise, that they make when they are scared or nervous, but in every thing ive read it state's nothing saying they are a mean animal?, i just want to no how come it may be mad??, ive tried everything i can to touch him and every tiome i get 3 inch's from him he freak's out!, can any one answer why my sugar glider mean????