When I was pregnant with DD she would have days where I swear she hadn't moved at all. I ended up at the hospital hooked up to those machines that monitor them three times because I swore she hadn't moved all day.

She had been moving, but due to the way she was facing that late in the pregnant, I just wasn't feeling it. The monitor was going off, yet I felt nothing. It's a good sign though, it means she's spine to the front (and as such all legs and arms are to the back where you won't feel them as much) and that's a good birthing position!

If you're ever worried though, ring your hospital or OB. I was meant to give birth in a birthing center and they said to call any time.