Spacing in breast feeding times.. help

Jessie

So my son will be four months old tomorrow, he’s went from nursing every 2.5 hours to every 4-4.5. He’s having plenty of wet diapers and his weight gain is phenomenal. He weighs 19lbs 13oz as of yesterday. I took him to the doctor because I’m concerned with the gap in his nursing sessions but they aren’t concerned at all. Is this normal?