Cramping/Twitching after sex?

Katie

My husband and I are on our first round of TTC. I've noticed that a couple of minutes after he (as he so eloquently puts it) "blows his load" I have some very minor cramping/twitching in my lower abdomen. Nothing that I'd consider remotely painful at all. It maybe lasts for a minute or two, then goes away. Not considered about it, just something that I'd never noticed before we started TTC. Anyone else notice this? Any idea what it is?