I've been playing through some of the bonus levels in the Gringott's Vault, and noticed that the bricks in vaults 3, 7, and 9 are red, while all the other bricks are green. Is there a particular reason why three of them would be red? I though maybe it meant I couldn't complete them yet, but I've played through them and had no trouble completing them. Just wondering what the difference in color meant, if anything.
From this GameFAQs article, It appears that the different colored bricks can be collected to gain additional achievements.