I don't think Matt is a hero reborn anymore than Perrin is, they both have old blood in them, both are ta'veren, but not heros reborn. When Matt was in the doorway, he said he wished the wholes in his memories were filed, he did not specify with what. So the fox people just filled em with old battle memories. I wonder when we will learn how the dice ter'angreal accidently (or maybe not) got used around Matt when he was in the tower. He doesn't have his luck until after he leaves the tower, and can it be coincidence that Verin describes the dice ter'angreal to Egwene? RJ doesn't throw in information for it's own sake. The dice ter'angreal make luck go wild, once a coin flipped landed on it's edge one thousand times in a row or so. I'm betting that it got used somehow around Matt, giving him his luck.