I'm a little late to this thread, and it sounds like they are going to replace it for you. Hopefully you have better luck with the next gun.
Looking at those pictures, it doesn't look normal for only 50 rounds. My guess is that it wasn't properly prepped as it looks like it's starting to flake off.
Now that said, I have a fair amount of experience with both Cerakote and DuraCoat. I absolutely hate both of them. I don't understand why people pay to have perfectly good firearms refinished with either of them. Especially when Glock will refinish your firearm for a fraction of what most of the custom shops charge. Other firearms, I can understand I guess if it's really rough, but even then I'm not a big fan. They are better than spray paint, but that's about it.
Neither hold up anywhere near as good as the factory Glock finish, or good bluing, etc. They start showing holster wear pretty quickly in my experience and start looking pretty rough simply from carrying them. The finish also wears off on contact points (although not as fast as you're experiencing), etc. If you throw them in an ultrasonic cleaner, it also has a habit of taking it off in places if it gets too hot. This is not an issue with a quality finish on the gun. It really just isn't a durable finish and if you use or carry your gun, it won't look good for long. Once it starts wearing off, it looks significantly worse than the factory finish would have.
