Bantum vs Standard growth development question?

I've inherited some EE bantum chicks and noticed that their breast bone feels much more prominent than my standard size chicks did. They're feathering out just fine and act healthy as can be, but now that I've noticed the breast bone I'm worried about their growth. Is this just a normal difference between the different sizes?

I didn't get the chicks until they were about a week old. They'd been hatched and raised by the broody hen. They were starving when they got here. If they'd been undernourished wouldn't they have caught up over the past two weeks of me pampering them?

Am I just paranoid? Is the inner control freak in me out of control? It's okay if I am. According to my family that's a common occurrence.