Hi Allan,
The only thing I can think of is because the fly is tied in sizes 10 -14 it is too big to be called a Gnat .
On the other hand it is amazing what people will do for the all mighty dollar and a slice of fame. While off point to your question, Ron's and others observations are dead on. I too had a "pattern" ripped off from me. Got a call" How do you tie it" from a tier who was going to tie my pattern because my price was higher than the guide wanted to pay. The fly, which I renamed in one of the phone conversations is the Stimulator.
My advise to the teenager who's fly was ripped off is to go back to the fly shop with his parents and demand an explanation and a correction or they will be hearing from your attorney. It is quite sad that it has come to this but what is right is right and what is fair is fair. I'm sure that the shop wouldn't want to even consider the costs of litigation if they knew they were in the wrong. Nip it in the bud, it will save you years of agitation, no matter how much you try to let it go, if your pattern becomes popular.

Alan, I say write to the magazine and point out there error. How they respond to your letter will clarify your perception of the author and magazine.