The excellent mechanical condition might suggest this bike doesn't get much use. A lot of these bike owners don't think they need to check the pressure in their tires after the bike sat for a month unused. Not saying that's your case, but you haven't given evidence it's not.
Who saw the tube when it was put in? Do we know that the shop did anything but put air in the tube and never removed the tire? There are a lot of people that can't put air in tires themselves and ride with almost flat tires. That'll wear a tube out quick.
If I change a tire, I will reuse the tube.