It's a worry.
I took a paint depth gauge with me when I bought the wife's GTi. There were 2 ex-demo's and I was assured both were genuine. Look on the sales guys face was quality when I pointed out areas of paintwork on one.
Don't beat yourself up, I found an area of localised paintwork on the bumper of my car after 4 months. Luckily an afternoon with wet and dry and a polisher sorted it. I always thought I would spot everything.
Good luck
