My NW flight on Monday from Phx to Dca was originally purchased as a connection through Mem. When I checked in at the kiosk out popped a single boarding pass. NW flight 296 was now a through flight. I had the same seat (4C) all the way. On the ground at Mem they announced an unscheduled aircraft change. At the new gate I noticed several groups of pax from the first segment also making this through connection. I am curious to see if I get the segment miles or just the "through".