Baby breathing

He's 5 weeks now but ever since he's been born he will breath normal when he's sleeping or very calm. But other than that he breathes all fast and loud like he's got something in his throat? Hard to describe but it's like he has to clear his throat but can't do he sounds like a little pug or something always making noises when he breathes. I know he can breath normally because like I said when he's sleeping it just sounds like normal breathing. No grunts or that phlem sound, anyone else's babies do this?