What you described is very typical of many subocs. Most of us who keep more than one have individuals like that -- because they are ALL individuals, and I think sometimes people expect them to be otherwise (it's very easy to do so, speaking personally, LOL, but these are vehicles we've only barely begun to understand), and such expectations are not very realistic. As you and Mike said, those individuals are not anorexic or emaciated, despite the finicky eating behavior, and do continue to grow (even if it's not as fast as WE would like). In fact, finicky females like that will often lay healthy clutches of eggs.
One of the paradoxes of captive-breeding is that the animals that are best-adapted in demeanor, genetics, behavior, and color for a natural life in the wild are often the worst candidates for captivity. They are tuned in to their age-old genetic wiring to HUNT -- not be offered a proverbial microwaved corndog on a paper plate (whether it be live or frozen/thawed). So, we are essentially selectively breeding snakes that are fit for a wild existence right out of the captive population, whether we realize it or not. Sorry to get so philosophical LOL, but all the same, these are phenomena that are everyday common occurrences and topics in ex-situ (aka captive) conservation biology, and it's something seen in every captive population of any species in the animal world.
Dusty R.
Suboc.com -- captive-bred Desert Ratsnakes