One of my Sedum rupestre 'Angelina' developed an odd form. Its foliage formed in the shape of its typical flower clusters. Does this normally happen to this kind of sedum? Is this some kind of mutation?

Normal! An old flower stalk— new branches forming on a spent flower stalk. If you look closely, you can see some sedum fruits!

Ah, that makes sense. That explains why it looks so much like a flower stalk. Thanks!