doppler bothering baby??

pathfindermon

I rented a doppler.  I love being able to hear the lo's heartbeat!!  It's so reassuring.  But the little peanut always moves away from it.  I'll find the heartbeat for about 10 seconds and then its gone.  Then I'll find it again and it moves away again.  Does anyone know why the lo moves away?  Is it the noise or the pressure?  I really hope I'm not hurting or bothering my sweet-pea!!!