One troubling aspect of this is that it appears Alaska had reason to believe something was wrong with this plane but basically ignored it. They were getting pressurization warnings on prior flights, but the only action they took was restricting the plane from flying ETOPS routes. They're the dominant carrier in my area, so these sorts of screwups make me nervous. I can't easily avoid using them without a fair amount…
Things like this are always alarming until you learn the base rate. Unfortunately, I cannot find a quick reference for this, but many many flights take off with some anomaly noted in the technical log book.
I have never seen a 100% serviceable aircraft, as far as I'm concerned a aircraft where everything works to spec and the spec works to needs is a myth that we strive for but can never achieve.