Dance Dance Revolution Mario Mix shortage in the US only?

Yesterday Joystiq pointed out that Mario’s breakdancing days might be over. While this *might* be true in the US there’s no signs of this for the UK or Japan where the game originally launched in July. Amazon prices haven’t been hiked up in either of those regions, in fact the game remains in stock.

Amazon links: US ($118), Japan ($52), UK ($52), France ($58)

If there was a problem with the mat why hasn’t Nintendo pulled the game from other regions too?  Without Mario Mix around it is up to Fire Emblem, Super Mario Strikers and Mario Party 7 to carry the Gamecube through the holiday season.