I've bought directly from Aquarium Masters back in the day, they turn out decent stuff.
I checked out all of the stock tanks my LFS had. They all looked solid. My tank was a custom build with the overflows, but it still looked after my initial inspection to be as solid and quality as what I observed in the LFS.
Obviously, there is no way to visually see if there is a defect in the glass itself in a situation like this. Clearly this is a defect in the ribbon itself from the glass manufacturer, not really a fault of the tank builder. That said, the builder should assume the culpability for a failure such as this. even though the fault is not their own, they built and sold the tank.