I'm migrating to a new MacBook Pro. Both are using the exact same Yosemite OS and migration assistant was humming along using the thunderbolt cable when all of a sudden when I'm supposed to have 6 minutes left I get a message saying 26 hours left and it suggests I use a thunderbolt cable for a faster transfer. Nothing happened at all (no one touched anything, unplugged anything etc) and now it seems to be using wifi. What gives?