Three weeks old with little bit of mucus in poop?

Ja

I just changed my 3-week-old’s diaper and noticed a small streak of mucus that was stuck to his bum. Never had this with my daughter. He’s exclusively breastfed, doesn’t have any problems that I’ve noticed. The mucus was the same color as the little bit of poop that was in his diaper (yellowish-green). Anyone knows what this could be and if I should be concerned?