Hi, I just noticed my front fork was leaking from the shock
Is this something serious that I should have fixed right away? Or can a wait a bit? How much should it cost to fix from a dealer (replace O ring?)?

 

Too many wheelies. Sounds like your fork seals are leaking. It's a fairly simple repair, parts are pretty cheap. A couple of hours of labor though, unless you want to try it yourself.

You should fix it soon though. You don't want to ride the bike without a proper front suspension. Stability will be thrown way off, especially during hard braking. Also, is the fluid in the fork gets on a brake rotor you will have ZERO stopping ability. You should get it fixed soon.