Fumie was the last skater, so you could say Yoshie was jumping up and down because she had just won the title. But given what she had said about Fumie (or didn't say), it may be more than that. I just remembered how Yagudin was criticized for pumping fist over Plushenko's fall at 1998 Worlds.
I didn't see it myself (or Yoshie and Shizuka flashing the victory signs in front of TV camera). So maybe someone who saw the NHK coverage can put all this into context.