Well, I guess I messed up pretty good. Rested the brisket for an hour and when I started to slice the meat was shredding all over the place. I know I was slicing against the grain (I marked the grain with a slice before the cook began). I'm assuming that the shredding of the beef is a characteristic of it being overcooked?
Oh well, I guess despite all that, I now have some decent meat to make shredded beef sandwiches, tacos, etc.