Jim crosses his arms over his chest, and pulls the disguise back over himself. Well, why not? He might know who Lecter is, but he's not going to give himself away.

It's a little like someone pulling an invisible sheet up their body. Subtle changes all the way up; a push out of his stomach, a drop of that shoulder, a minute slackness added to his jaw. Only someone good would notice the change in progress, but just about everyone would be fooled by the finished product.