SOME newly made Gen3 Glock 19s have had the same ejection issues the Gen4s had as well. That said, I really wouldn't worry about it. If you do get one that has an issue, just call Glock and they'll replace the part at $0 to you. They stand behind their products and will do whatever it takes to make you a fan boi too!
I have one of the early Gen4 19s with all the issues and Glock was great to deal with and it runs like a champ now.