Baby Acne or Rash?

Hi mommas! My little Evelyn is 4 weeks old today! Time is flying!

I noticed this on the chest, under the chin area, when changing her diaper. It looks like the baby acne she gets on her cheeks.

Is it normal for a baby to have this on their chest area? Or should I call them on call pediatrician?

She is acting like her normal, happy self. She's eaten well all day (formula fed same formula since she was 4 days old) and had 6 wet and 2 poopy diapers today.

Just not sure if I need to be worried about it or not...