If you are using the handy package enumitem in version 2.1 or earlier you could consider to update it. The author Javier Bezos announced v2.2: “This release fixes a bug in some description styles (the first label in the first list after a description was wrong).”
I did not encounter that error yet, but I’ve noticed a different behavior of v2.2 and v2.1 with the example Javier posted here in his forum.

For update or information visit:

• enumitem on CTAN
• the Homepage of Javier Bezos
• the enumitem page on Javiers site
• the enumitem forum also hosted there.