Master Cylinder leaking?

[White70C20]

Last Friday I changed/rebuilt my front drum brakes. I checked to make sure the master cylinder was full when I got done. I drove it around town a little bit and pedal is still soft. It still goes almost all the way to the floor.

Anyway, that's not what I'm asking about today. After I drove it around on Monday, checked the master cylinder to see if it was still full from before I did my brakes. It was at the same level. However, I did notice a drip coming from the underside of the master cylinder near the back.
I had noticed this once before, but the brakes had worked fine until the front shoes de-bonded.
It dripped once or twice in the 5 min I was looking at it. The reservoir is still full. It appears to have a thin amount of brake fluid running down the side of the reservoir in some areas (just a small dribble here and there). I had a new master cylinder put on shortly after I bought the truck a year ago so the reservoir lid/gasket should still be sealing ok right?

The master cylinder fits tight against the booster, so I know it's not leaking there.

As always, any suggestions will be appreciated.