my 4 month old baby boy is not drinking milk properly everytime he is just sucking for 2 to 3 mins and leaving..is it normal can somebody please tell me??

A. sucking 2-3 mins baby may be getting full as you nurse the baby milk gets denser and thicker so baby may take for less time than earlier if pee count is around 6-8 times and baby is sleeping well then baby is getting sufficient amount of milk