The pump itself is three years old, and of that three years, I wasn't riding probably 1.5 of them. I'm thinking that the first tube was likely damaged when the shop took it off the niner, probably not expecting I'd try to use it again.

Going with slime tubes because it's much cheaper than converting this bike to tubeless. Both times it's flatted before this debacle were due to thorns stuck in the tire which is precisely what the slime should be able to prevent. Though if it was a lighter bike it wouldn't be worth the added weight.