Well, yes and no. To be honest, I am not sure that the carry on scanners are really sensitive enough to show a probably sedated and sleeping tiny little cub.
I find it more worrying that the Japanese government has raised concerns with the US over increasing number of passengers connecting at Narita from the US with guns in their carry o on. Guns that the TSA fails to spot.
Guns should be spotted, cubs are debatable I think. That being said, people snuggling wild life should really be caught and stopped.