I get this all the time. When I started programming there was no Internet or Stack Overflow to help me, there was no option for me but to read big thick manuals.
It can be threatening when someone waaay more capable than you joins the team, but you have two approaches. You can feel threatened, or make the most of it.
For example, I work for a company who hires extremely smart people, and frankly they make me look like a doofus sometimes. However, I relish the chance to work with these guys. Mainly because there's a LOT I can learn from them. The field of software engineering is so vast these days that it's impossible to keep up with all of it.
So the other day, a colleague of mine gave me an awesome demo of what he's been working on using the new Spring Cloud, and it was great. I learned something new. And that's what I love about working with really capable younger programmers. They have no fear, they're willing to try something and so what if it doesn't work? And that's starting to rub off on me.
Now the flip side of this, is that I have something the new guys don't. And that's experience, and excellent communication and presentation skills. (I worked as an assistant pastor for a small church for a while and had to preach, so that's where I learned that skill.)
So they'll often pop over and ask me how to present something to a group of directors, or just bounce ideas off me so they can explain something really technical to folks who aren't that technical.
It's a two way street if you approach it right. It's easy to feel threatened, but at the end of the day, there's ALWAYS going to be a better programmer than you somewhere, and they'll be younger too.
So don't worry, you've got nothing to prove, just keep updating your skills, and make the most of the learning chance you've been given :-) And enjoy it