Is my 3 week old eating too much?

My son was 3 weeks on tuesday, up til now he usually eats about 2.5 to 3.5 ounces every 3 hours. However in the last couple of days he is eating every two hours, and eating almost 3.5 ounces every time! Yesterday he ate almost 30 ounces in 24 hours. He was only 6lbs 10 ozs at birth, but has been putting on weight steadily. Is this normal, do you think he's having a growth spurt? I'm just worried about his little tummy getting too full. Thanks!