It wasn't a change of equipment, as they had this int'l configuration in the system when I made the reservation, which is one of the reasons I transited Chicago rather than flying N/S from MSY (also a better departure time, and I wanted to check out the EMB 170 R.J.). I didn't expect to be double upped when I purchased the ticket at the airport, but when I saw the seat assignment, nor did I point out it was a three class.