Baby boy superrrrrr low!

Had my 15 week check up yesterday. Normally I feel him on the left side aligned with my belly button. So the nurse used the Doppler to hear his heart beat and she couldn't find it! I was getting super super nervous. It took her like 5 minutes and still nothing. So she eventually pulled my pants a little lower and put the Doppler very low and sure enough there be was with a rate of 156! He sure was low just like his brother was the whole time! I'm just glad we were able to hear him :) anybody else's babies laying really low?