What to do for this sedum? (yellowing leaves)

As you can (hopefully) see from these photos, the sedum is doing quite nicely, but the leaves are yellowing and, as the second (poor quality) pic shows, even curling in some cases. I'm wondering if I should be applying some sort of treatment, pruning the plant, or snipping the leaves. Most garden books advise removing affected leaves in cases lie this, but this would mean virtually all of them! I should have maybe picked up on it in the early stages but have not been home much...

 

That particular sedum dies down in winter, best to remove the stems during the winter, new ones will grow next year.

 

Thanks Pete. By remove I'm taking it you mean cut it right back to the base?

 

I have the same Sedum Simon and leave mine to die back fully. In early Spring you should be able to pull the old stems away gently and will see the new ones already budding underneath.