From my experience younger animals are voracious (especially at the size you are mentioning) and will very rarely go off food, of course there are always some animals that will be the exception to the rule but for the main part they should be eating.

All the animals I have hatched or bought in 09 are eating and are still pretty much in their feeding frenzy period.

Of course some has to do with husbandry and what you are feeding also.

Keep the young ones in tight and warm enclosure and they will eat like champs for the majority of them.