Yeah, it does sound a bit silly, but I've had that sensation as well. I'm not taking any sort of sleep pills or anything, so I doubt that it can be from that...but I'm no expert, so I dont know. When it happened to me, I thought it was just some sort of muscle spasm. I never really paid it much more mind, aside from it being annoying occasionally, because there are many other sensations, tickles, aches, pains, pricks, itches, and so fourth that my body has. So if I spent my time searching for the source of them all, I'd be in debt from the medical bills, lol. But if it really bothers you too much, talk to your gyn to see what he/she says might be going on.
Fill me in too