Canada at $4+ a gallon? Were those Canadian $? If so then you paid the same price as US$...........
Actually it works out to about $4.49 Canadian equals $3.99 US -- so here even in NoCal it's running still anywhere from 70-95 cents a gallon cheaper in the US. I was paying 1.15 Canadian per liter/ 4 liters is just a little over a gallon( 1.06 gallon)
handy, dandy currency converter
http://www.xe.com/ucc/