I've noticed that Malu will shiver sometimes. When I first got him a couple weeks ago, it was pretty cold outside. I figured it was because he was cold and it still may be the case.
For example, today I was in the Kitchen (which is gated off to him) and he walked up to the gate and was shivering. I sat down at the table to eat. He then snuck behind me and peed on his bed (he sleeps in his crate, this is just an extra bed that he uses sometimes when I am working). I took him outside and he played and ran around a while. Its probably 45 or 50 degrees out and he wasn't shivering outside at all. So I'm kind of stumped.
I don't think he was shivering because he had to pee. He'd been out an hour or two before. There may not be an issue at all, I just was wondering if anyone else has experienced this. Oh, and he's about 11-1/2 weeks old.