I would say it was quite possible that your GP could hear something was a bit different but using the doppler meant he couldn't hear or track it well enough, and couldn't monitor for long enough to see if was an one off blip or an ongoing thing, so he send you to hospital where they could do more accurate tracking and get better information about the HB. So I wouldn't necessarily say he was wrong, just may not have had the tools available to assess it well enough so sent you where they did have the tools available. Glad to hear it was all good