Well, first thing sounds like you were on the edge of a fullblown LD. Sometimes no matter how badly we want to, our brains will not let us get lucid.

The thing about moving your arm sounds to me like you werer still al little bit in sleep paralysis.

I've only experienced two full-blown sleep paralysis episodes. It felt like my entire body was so heavy that no matter how hard I tried, I could not raise a head or arm. Really cool!