That's an option, though I doubt it because of Faile's actions at the beginning of tGS. We do see some of the changes starting before he shows up in Ghealdan as the Prophet. At the end of tGH he suddenly treats Rand with a modicum of respect once he realizes Rand is the Dragon Reborn. He then declares it is his responsibility to spread the word of the imminent coming of the Dragon (kind of like a John the Baptist deal from the Bible). So if Demandred was involved, it was probably (though not necessarily) after this point, and he just saw an opportunity to cause some Chaos by twisting Masema's idea (and mind).