3 week old snacking at breast ??

So my 3 week old has got into the habit of snacking like on breast for 2 mins then 5 mins then 8 mins being the longest every three hours some times earlier then 3 hours during the day.... at night he'll eat on average 8 to 15 mins sometimes he'll go for 30 but that when he sleeps a 4 hour stretch at night is this normal im worried he something is wrong but hes not really taking a bottle anymore for me is it okay to wait the four hours instead of waking him up to feed cuz rejects the breast when i try to keep him up and make him eat