I don't get why people would even comment on such a young childs weight..
Because people today are so obsessed with weight that they will even make perfectly normal and healthy children out to be fat!!

DD1 was in a similar weight range at that age and DD2 is looking to be even bigger, she is just on 4 months and only fits into size 0!! (and she is exclusively breastfed - and i am sick to death of hearing "isn't she big!!")

Ask them how much they weigh - I find it usually shuts them up!!