baby movement

So I know kick counts aren't needed/reliable until further along, im 21 weeks. But should I worry yet if baby doesn't feel as active in a day? She's normally constantly rolling, kicking, punching, all kinds of active. But today she's seemed very quiet. I have felt her, just not nearly as much as the usual. Is it okay since I'm just at 21 weeks? Or should I be doing something, calling the doctor or anything?