This is after, on the way here, the following occurred: we pulled away from the gate; sat for a bit; the pilot announced "we have a quick maintenance issue"; we sat for a while; the pilot announced "there's a light on and we need to check it out"; we sat a bit longer; the pilot announced "we're going to pull back to the gate and reboot the plane"; we did so; the pilot said "ok, we're good to go." The delay ended up being about 40 minutes.
Overall I like Alaska/Horizon, but I think maybe it's time for them to get some new planes.
UPDATE: A new announcement that "The plane should be ready to go at 9:45 PM" (original departure time was 8:55 PM). I stand by my recommendation of new planes.
UPDATE 2: We finally left at around 10:00 PM, arriving in Sacramento at 11:40 PM. The plane managed to make it all the way there.