shivering kitty

my kitty was shivering today. that's the best I can describe it. He was sleeping and I just noticed that his whole body was shivering. It's not the same thing as when he gets little twitches during REM sleep. I've seen this every once in a while when he's just standing too; his front legs shake for a few seconds like he's unstable. Also one day I was holding him by the front door and he started to shiver. That time I just thought he was super excited because he always gets excited and mews when the door is open (He wants to get out).
So anyone know what's up?

I always figured when a cat shivers they are scared or cold and my automatic response is to cuddle thyem closer to make them warmer and more secure.

Is that fact? Heck if I know! Maybe someone will let us know what it's really about.

how old is your kitty? Are there any neurological symptoms?

One of my cats, who is terrified when a stranger comes into the house, does this when a stranger comes into the house. did that make sense?

I have two kitties. One was doing this for a while and then it just stopped?? Never did figure it out. I'm obsessing about all kinds of other kitty idiosynchrosies now

okay I've not responded in a few days but if anyone is still reading this...
He's 1and a half and as far as I know has no other neurological problems. I don't know what else to look for though. and no there weren't any strangers, but the time at the door he was excited/anxious. mabye he was dreaming of something very exciting? I think he takes after me though as I have a tendency to "shiver" when I'm anxious.