I had the same thing happen! His leg/hip joint was very loose, and one of his arms didn't bend...
...I sent him back. I just got a new one, his leg is good now, but both his arms wouldn't bend, again! So I got a little frustrated, and decided I would try forcing his arms, a thing I normally wouldn't do but I figured I had nothing to lose, and to my embarrassment, his arms bent! They are extremely stiff, but I figure they will loosen up with time (and anyways better stiff than loose!)
Which joint is bad on yours?
Did you notice the detail on the hands and feet?