Irregular heartbeat

Autumn
Had ultrasound yesterday and they said baby boys heart beat was irregular- never had an issue before and I'm 33 weeks always sounded perfect they insisted it was because I ate chocolate and dr didn't seem to worried he's also 7 pounds already so I have to go back for a 3rd one hour glucose test even though I passed the last two with flying colors- they keep telling me no to worry but how can you not- anyone else have an irregular heartbeat that turned out okay?