Baby movement

I'm almost 38 weeks and I've noticed over the last month that my baby is way less active on the days my BD and I have sex. Usually she is going crazy all the time, so much that I've never actually felt the need to count kicks at all. My BD and I usually end up having morning sex on the rare occasion he's in the mood for it and then the rest of the day my baby isn't crazy like usual. Anyone else experience this? I'm not really worried, just curious.