What signs does Jekyll give that he is troubled, despite his assurance to Utterson that there is no problem?

Two weeks later, Dr. Jekyll is holding a dinner party at which Mr. Utterson is a guest. Jekyll looks tired and weak. After the guests leave, Utterson confronts Jekyll over the matter of his will and tells him that he has been learning about Mr. Hyde. Jekyll becomes upset when he hears of this and tells Utterson to drop the subject. Utterson urges Hyde to confide in him, but again Jekyll tells Utterson to leave the subject alone and assures him that he can be rid of Mr. Hyde at any point.