Hi,
I have to say, I was getting breathless quite early on actually, and had exactly what you described when talking to someone at work - more than once. I also had some palpitations, but MW said it was just that your lungs do have to do a lot more work as you have more blood to pump, and also your organs move and your lungs get squashed etc.
I'm sure it's fine but if you're worried, it's best to get checked over.
Hope all is well.
Cath