€1 buys nearly $1.50 is more to do with it I would think. US prices were cheap the middle of last year. They are now crazy cheap.
I wouldn't be surprised if TLC don't raise more US prices. The whole thing with Canadian retailers looking for price-matching shows they are pretty stuck otherwise.
Dwarf Mine
Regarding the price increase, the 7905 Building Crane went through a similar phase. In the US, I believe it was a Target exclusive (never showed up in retail in Canada) and was $50 at first. However, LEGO made a second, smaller, production run of this set. Consequently, the price went up to $60.
-Bryan