Baby sleeping habits

Didi

Ok I have a new born 4 weeks and the last 2 nights she has slept a 4-5 hour stretch then back to 3 hours, is this something I should worry about she’s not under weight by any means and she Eats plenty every 2-3 hours during the day but the last 2 nights she slept a little longer then normal at night has anyone had this happen this early?