Trying to avoid starting an entirely new thread...

Here's my Q - I've got relatively few options for a connection in SEA next week, but I've found something that gets me in on Alaska Airlines (Concourse C or D) at 2:40pm and out on American (Concourse A) at 3:25pm. That's only a 45-minute connection, and I'm wondering if anyone can shed light on whether that is too tight to move between the concourses? I'll be in the first row of my Alaska Air flight (thus can get off quickly) and don't mind being the last one on the American flight. I can move pretty quickly through the airport and am not checking any luggage. Thanks!