Leaky brake issue.

[Isaiah92260]

So I did a 67 dual master cylinder conversion on my 63 a few months ago. Split the lines in the front with new lines and fitting, I went as far as using one small wrap of plumbers tape on the threads and even used thread seal cuz I was having leaks still I guess cuz of my flaring work.
Anyways never had a leak problem with those..... Lately I noticed my brakes getting low. So today I finally got a chance to check all my fluids and noticed my front Brake resivours was low! Now I didn't replace the front soft lines, I know I will have to soon, but I saw no leaks. Now I did see a little dirty was and one small leaks trail on the drivers side on the front wheel under the hub cap, when I did my lines I noticed when the week was off is was black and some what most around the brake cylinder, I'm sure that maybe the problem? But I did my brakes in March, it's been a while since the finally went down. In this picture you can see when're do just added new fluid, and the front resivours for the rear brakes are dirty, I new that's because I didn't replace the rear line.