What might cause an odor coming from my kitchen sink drain?
It has a disposal which has been run recently and is working fine but the smell is persisting.

Any ideas?

The smell may be coming from within the pipes themselves, for a temporary relief take an orange peel or lemon peel and grind up with the disposal. You can also get some drain cleaner that is safe to use with a garbage disposal, that will get rid of the food inside the pipes.