Less movement at 24 1/2 weeks?

My son has been pretty noticeably active since around 19-20 weeks, but this week it's like he's super lazy or something in there. It started Monday all day, and I had a dr appointment on Tuesday at which my dr said his heartbeat sounded great and that he was happy in there. I figured it was just an off day, but now it's Saturday and I feel like he's still not moving a ton. I have felt him here and there, just not as much as I did in the few weeks before. Normal? Or should I worry?