It also may depend on what kind of airline ticket you purchased. Frequent flyer tickets cost you miles plus the US airport fees - which there's a maximum amount that can be charged depending on the airports you fly from/connect through. If your taxes seemed a little light (adding in the $36.50 should be noticeable) as in my case for traveling this fall, I believe I should be prepared to pay the departure tax.
With other tickets, purchased directly through the airline website or through travel sites, it may be harder to tell if the fee was included because it may be included in the purchase price before US airport taxes are added in.
But then again, what makes sense, it's always true :rolleyes: