Thats an seamingly easy fix... but let me tell you about doing it on my TJ.
I thought the thing would pop right out... HELL NO. I pried... whacked... use vice grips... all to no avail. Drank a 6 pack doing it smoked about a dozen cigarettes and cursed enough to gurantee myself a place in hell. Then I stepped back for 5 minutes and contemplated giving up. Picked up a screw driver for one last try and the friggin thing popped right out. I was so pissed. I through it across the garage and broke a window.
Anyway... axle seal leaks happen. They are no big deal as long as they are dealt with in a timely manner. You can get it replaced for warranty.
I have the same problem... but I am going to Paragon again soon so want to wait till after that to take it to the dealer. They will replace it though, I a leaky seal in the transfer case and they had no problem taking care of it for me. As long as it isn't dripping out, you should be ok for a while... mine is just dusty from the little bit's of oil that attracts the dust like a magnet. Just keep an eye on it.
Also remember before you take it to a dealer for anywork make sure it's clean on the underside. If you have a ton of scraps on the bottom just give them a blast of flat black paint. It only take 5 minutes and it also keeps the rust off. If they think that you totally abused the Jeep they will black flag you and not cover it then you will never get those items replaced. Don't let this keep you from having fun though. Just be smart.