Hm, that doesn't look like something that would've been caused by TWA or the magnets. Was there a seam at the binding there initially? And if so, could it be spreading a bit? Is the crack below the finish or is the finish cracking?
Do you have a nitro finish on your guitar? If so, it could be nitro finish sinking into the binding seam. That's what my assumption would be!
Gav Brown