I'm not sure if this is helpful or not, but AS has two different configurations of 737-900s. The default for pre-reserved seating has the exit rows at rows 15 and 16, which is probably what was loaded for your flight when your seat was originally assigned. If your flight was assigned (within a day or two of departure) one of the newer 737-900s (with a forward lav in coach), the coach rows all shift back one, so the exit rows are at rows 14 and 15.

When that happens, it's not unusual to see people bumped out of the exit row.

Sorry ... Kinda stinks.

... Edited to add - I just looked up flight #25 BOS-SEA on 17Oct. This is exactly what happened - sorry.