... SERIOUSLY?!

I recently had a family emergency to tend to, and had to push back an award ticket (LGA > YUL) by a day. I spoke w/ an AA rep, and she made the change immediately. However, she noted there was a fare difference of $7,10 between the taxes I paid ($53,60) and the taxes now assessed on the ticket. I asked her why there was a difference and she cited currency fluctuation as the reason.

Unsatisfied with that answer, I did a little research on OANDA.com and determined that the change in rate was ~$0,01 between the time I purchased the ticket (12 Oct), and the time I changed the ticket (13 Nov). At best, a change in currency would've yielded a fare increase of ~$1,50. Yet, this is still way less than the $7,10 I was assessed, so I contacted AA.

Apparently, on 5 November, AA had implemented a "custom users tax" on all tickets issued departing out of the United States to Canada, Mexico and the Caribbean. The response indicated: "This is a new tax that had to be collected on your ticket inasmuch as you changed your itinerary. The tax will be paid to the government."

So, my question to the learned folks of this forum: is this another BS "tax" like BA's YQ?