Well, thankfully the discrepancy wasn't worse. Your weight can fluctuate by 2-5 pounds a day. The best thing is to do the official weigh in at the same time each week, with the same food/drink consummed and in roughly the same clothes. Full clothing weighs 3-5 lbs as well so keep that in mind. If one pound bothers you this much I highly recommend making your weigh-in-wardrobe and other details very consistent and you'll be happy as a clam while you lose lose lose.