In the scene where Phoebe and Paige are asking how all that happened with Piper, Patty and Grams Coop appears. (Just before Chris and Wyatt had arrived from the future). When Coop appears he says to Piper: "Thanks for telling me she's not dead". Why would he say that? Time had been changed and he wouldn't know about that. Coop knows that Phoebe is dead when Piper gets to Victor's house and says it to Coop. When they changed time that moment never happened so Coop never would have known Phoebe was dead and he would have never said that to Piper, except for the possibility that Coop exists out of the timeline since it's his ring and he may be connected to it.