Pea-size lump behind the head?

Vee & her boys👣💙

Hello Boy mamas my 4 Weeks old has a Little bump behind the head just right of the fontanelle. It hasnt grown in size and its not painful or swelling but his first appointment is only in 10 Days. FTM so I dont know if I should just keep tracking any change or if its worth getting him checked right away.