Well, sure, that has definitely happened. If we use that criterion, then the answer to every question is "yes," since it has happened to someone. In that case, there's also no point in asking since the answer to "has it ever happened" is already known. I have a feeling that the OP was asking if this was an elite perk, rather than if anyone, at any time has gotten an exception (like the examples you gave). If that is the case, then these things are well-documented, as noted, and easy to find. If it's the "has it ever happened" the answer, as always, is "yes."
Cheers.
One time, at band camp.............
Agreed.... The fee applies to EXPs. If it isn't documented as a benefit, you might get it waived, but don't bet on it. It's a fee that would only benefit a small percentage, if waived, and I would bet it is even more likely the person traveling with the pet is on an "excursion" fare. That is, people traveling with pets are as likely to be on a business trip and paying higher fares.
There seems little point in AA giving up a fee that would only affect a small percentage of tickets purchased by EXPs.