Baby movements

I am 25 weeks pregnant and I’ve noticed over the past week that her movements have become lighter and I don’t feel very many firm kicks anymore. Half the time I don’t notice she’s moving unless I put my hand over my belly and really focus on it. I can feel her kick my bladder but her kicks have just gotten lighter. My placenta is anterior so maybe that’s it? I just wanna know if this is normal or if I should tell my OB Monday. Thanks