This happened with one of my other cars lately. I am a careful driver and guarantee that I did not curb then saw the bulge on the front left. The only thing I could think of was if it was the amount of hard cornering I do (milton Keynes, roundabout, all the stress goes on that left front tyre)
I ended up switching it with the one of the rear ones, and it lasted another year when I then needed to replace it for MOT. I think it could just be a manufacturers error. If the tyre was reasonably new you should complain and let them replace it for you. Even with bad curbing tyres dont do that.