George and Harris felt uncanny about Jerome's suggestion to pack the bag at first. Why did they feel uncanny?
The readiness with which George and Harris complied with Jerome's suggestion that they leave the entire matter of packing to him was uncanny because they had misinterpreted Jerome's suggestion. Jerome had intended that he would be the one to boss the job and Harris and George would potter about under his directions. But the two of them had thought that Jerome wanted to do all the work and hence they readily complied.