Harley-Davidson (HOG) shares fell 4.8% to 48.26 on Friday afternoon after Citigroup reported a slowdown in U.S. sales in the current quarter. Citigroup said retail sales for the iconic motorcycle maker only grew 1%-3% in April and early May after a 29% spike in sales in March. The firm kept its 61 price target and buy rating and warned investors not to interpret the dip in sales as a bad sign, as sales can change from month to month. But investors