Stubborn baby

So my baby is active in the morning, and I usually do kick counts then (and again before bed). Absolutely every single time I open up my kick counting app, she stops. Every time! It's like she knows or something. She does the same thing whenever I let someone feel her kick too, she just stops moving, no matter how much she was moving before. But then when we're at the doctor's office and I'm getting an ultrasound, she moves so much they have a hard time getting measurements or getting her heart rate. It's kind of funny, until I have to sit there longer so they can try to measure her.