I go to a lot of pop-punk/scene-ish shows in my area and around and, generally speaking, I'm the only person by a few years that can even purchase a beer...and I've got that beat by 6 years.
I also have few people who've stayed into this type of music, so I'd be going alone which can be fun, but for an all day event could be a bit lame. It's nice to have someone to share the fun with. Everyone I know has just become so damn captivated by J. Biebs, Nicki Minsomething and heyijustmetyouandthisiscrazybuthere 'smynumbersocallmemaybe to care about Warped anymore. Womp womp.
You're worried about being too old for Warped and your friends are crazy about Biebz?! Well then...
I think Warped is easy to go to alone. You don't have to worry about someone else wanting to see a different band, etc. If you have enough bands to watch all day you'll be entertained!