Is it normal to have shortness of breath even at 5th week going 6th week pregnancy?

It doesnt cause any great distrubance but i do feel like i need to breathe in more. And with the covid situation having to put on mask, sometimes on the way to work, like walking and on the train i feel this shortness of breath. Is it just me being anxious, or maybe its just heart burn? Wondering if anyone has this too?