Yes. I've noticed that trend too. A lot of today's teenagers spend most of the time on their phones to consume content and to communicate. Most of them use PC only for homework. I feel like the amount of time spent in front of the screen is the same, but not for the same purpose, and not the same screen. I was a teenager during the transition, the iPhone was released just on my generation's transition between primary and secondary education. Still, we all prefer laptops.
Naturally, since we spent bunch of time on PCs, we tried and explored many different things. I started learning HTML when I was 11 or 12, I don't remember precisely, but I discovered it accidentally. I found out about View source and how to save a web page (HTML), then I started playing with the code. This was enough to get me interested and I started learning HTML and later, programming. Today I am 23 and I work as a mobile developer. I heard a lot of similar stories, not just in programming, but for graphic design and other fields that use a computer as a tool.
The smartphone is simply not a creative tool, and it's not an open platform. You can't "peek" inside of a mobile app like I was able to peek into HTML. If I didn't, I would never discover it and it would never lead me to other platforms and programming languages. You can't see and play with raw files. You can't just open a photo in an editor, which leads you later into some creative fields like graphic design. Sure, you can "get creative" in Snapchat with your photos, but Snapchat is not a professional tool. When we wanted to edit our photos, we had to first get Photoshop, and learn the basics of working with it. Since it is a professional tool, it is an invaluable skill. I feel like this doesn't happen anymore. Applications like Snapchat are enough to fill their need for creativity and those kids are less likely to discover useful tools.