Welcome Calhere,
Im kinda new also but welcome to the bolt! I knew mine was bad because when I would get in my truck I would have no brakes (go all the way to the floor), but I could pump them and get a good pedal. If I sat and held it though the pedal would slowly go to the floor. I had an internal leak. The fluid was bypassing the seal and not holding pressure. You have an external leak. It does not necessarily mean you need a rebuild. It depends on were the leak is coming from. It could be from one of the brake lines that attaches to the master cylinder, or it could be leaking from either end of the brake cylinder itself. I would first check to see if you can identify were it is coming from. If it is a line tighten it up. If it is coming from the end of the master cylinder that has the screw cap...tighten the cap. If it is leaking out of the end of the cylinder I would go ahead and rebuild it. The whole rebuild kit was on $23 from Napa. If you click on my link for stovebolt and go to the 2nd page of pictures, you can see my rebuilt master cylinder. Hope this helps. Let me know if you need more info.
later
