Makes sense to me. Feasible that Lan killed him at Midnight as well. I don't particularly care who Gaidal is, if it's even revealed. It could be a hint that the world is not entering a peaceful state (after all, what's the point of having a 3000 year arc of prophesy and purposes spinning out heroes just after the big bang? ) but it's worth noting that the time distortion could play in with his age. If Rand and the Dark One are in some sort of time suck, it's possible if the child is particularly far away he could be a little older. He won't get too far ahead of Birgitte, but then again, she's probably late in rebirth. She was probably supposed to be spun out before the Last Battle with Gaidal, so her inclusion might mean she's behind a bit.