Why is Elizabeth hesitant when she learns that she will not accompany the Gardiners to the great lakes but to Derbyshire? What does this change of plans foreshadow?

Elizabeth's vacation with the Gardiners is delayed and shortened on account of Mr. Gardiner's work commitments. In the course of the trip they pass near Pemberley and Mr. and Mrs. Gardiner want to go see it. Elizabeth does not want to go because of fear of seeing Darcy, but she finds out from the maid that the Darcy family is not at home. This probably foreshadows a meeting of some sort with Mr. Darcy anyway.