A few weeks ago, Bob Johnson got an email from a US Airways employee that began, “They’re at it again.”

What was US Airways up to? At the beginning of the month, the carrier quietly added a new fee: Passengers who book a ticket through a travel agent but call the airline directly to make a change to their itinerary will now have to pay another $25 to speak with a phone agent. They were exempt from the fee before.

And here’s where Johnson comes in. Calling him a loyal US Airways customer would be an understatement. Johnson helped start a group called FFocus, which advocates for US Airways customers, particularly frequent fliers.

While he isn’t opposed to reasonable fees, he says this one makes no sense.

“US Airways defies logic on a minute-by-minute basis,” he told me. “This latest change is yet another example of the ongoing customer-unfriendly attitude of US Airways. Somebody explain the fairness of this new policy.”

I asked Jim Olson, a US Airways spokesman, for the airline’s side of the story.

“We have fixed a loophole,” he says. “Customers who purchased tickets at travel agencies were calling our reservations center to make changes and we were not charging the $25 fee. So in effect customers who originally booked through US Airways reservations were at a disadvantage to those who booked via a travel agent. We closed that loophole and are now charging travel agency customers when they call our reservations offices.”

There’s another way of looking at this: If you buy a ticket through a travel agency and you have to make a change through the airline call center, then you’re being charged twice – once by your agent, who adds a transaction fee to your ticket, and then again by US Airways, for talking to an agent.

Is that ridiculous?

Actually, it’s reality when you’re dealing with big airlines.

“Legacy airlines charge fees for full-service — telephone and airport ticket office — transactions, including full-service voluntary modifications of tickets originally made through any channel,” says Kristina Rundquist, a spokeswoman for the American Society of Travel Agents (ASTA). “These policies have been in place for many years.”

Seems US Airways is the last of the legacy carriers to close this loophole. Only JetBlue Airways, Southwest Airlines and, curiously, Spirit Airlines, don’t charge a fee to modify an agency reservation, according to ASTA. The other major domestic airlines do, and their fees vary from the nominal $15 charged by AirTran to an eye-popping $75 billed by Alaska Airlines.

But just because everyone else is doing it, does that make it right? Rundquist took the high road when I asked about the fee, saying only that, “the agency channel provides an enhanced set of values as compared to the direct full-service channel,” and then listed those benefits in an email.

That’s certainly true, but a little beside the point.

I asked Art Pushkin, another frequent US Airways flier and FFocus member, what he made of US Airways’ closing loophole.

“This is tantamount to preying on distressed travelers,” he says, noting that the people who are likeliest to be hit with this fee would phone the airline as a last resort, either when their travel agent is unavailable or when the must make a last-minute change because of a storm.

“They might pick up an extra $25 here and there, but what will it cost in lost future revenue?” he asks.

Olson notes that passengers can still make itinerary changes for free – as long as they use the airline’s website.

What do you think? Is US Airways’ fee added to your travel agent’s fee too much?

You think so.