As Guang wrote, the original Xi (Double Happiness) character contained a drawing of an 18th century educational poster. As I heard, that made harder to sell Xi Zhi Hao pu-erh in conservative China. So, the Xi Zhi Hao went the easy way and changed its logo.
Even the paper changed from hand-made to mass produced shiny white. Well, I liked the old style of Xi Zhi Hao more.