In what way does Roald Dahl inject the scene in the cider cellar with an extra layer of suspense?

The reader is already very anxious at the prospect of Mabel finding Mr. Fox, Mr. Badger, and the Small Fox within Bean's cider cellar. Then Dahl increases the level of suspense by having Mabel choose two jars that are right next to the jar behind which Mr. Fox is hiding. After Mabel takes two jars, the reader and Mr. Fox believe that all is well for Mr. Fox, but then Mabel calls upstairs to ask Mrs. Bean if she should grab a third jar for Bean. The reader knows that if she does take one more, Mr. Fox's hiding place will be revealed.