Why is my muslin (cheesecloth) sticking to my seitan?
The cheese cloth is porous enough for the seitan to expand through during the cook process. Try a looser wrap with the cheesecloth. If you steam it in the cheesecloth it will absorb less liquid and not expand as much.
When this has happened, I have had limited success removing the cloth and preserving all of the outer layer. If the seitan is not too embedded, let it cool on a rack 5 minutes and then try to slowly peel off the cloth. More than 5 and it is a hardened mess.