Shipping fees charging more to buyer than to seller?

[vintageparis]

I'm a little confused about Shopify's calculated postage rates.  I routinely sell to customers around the world, and specifically my orders to Australia and Canada lately have been charging the buyers high calculated shipping fees, but when I purchase the labels the fee I pay is much less.  This is for first class international shipping, and I don't have any special settings on that in my settings,.  For example, I had a purchase from a customer in Canada today, and they had to pay $39 in shipping, but when I bought the label it only cost me $22.  

At first I thought it might be a currency conversion thing, but I double checked and Shopify is indeed paying out the $39 to me in US dollars, so that isn't it.  Any ideas on what is going on?

[VM26]

I'm having the same issue.  I hope an answer is posted soon.