I am 39+1 and baby's movements have become less frequent. Ob says not to worry if you can feel 10 moves within half a day. Baby's sleeping longer so she does not move that frequently. Her movements have become less obvious, more like twitching/scratching, so you have to be stay still to feel then. Hope this helps to alleviate your fears. If you are still worried, best to pop in Ob's office for a check.
Same thing here. She is just running out of room to move like she used to. But I still can't help but to worry about it sometimes. If I get too bothered by it I will drink like a half a soda or a half a cup of coffee which I never usually drink and she perks up. Its enough to confirm to me it's just me being paranoid and that baby is just fine.
My baby has days just like that! I can feel her but very little, then days like this pass and she is very active again. I think there is no need to worry:)