Was playing on a server,seeing a sign going dark, walk to far it goes light again but becomes unreadable, walk in readable distance it goes dark.
Steps to recreate:
1) Look at my picture
2) Recreate it

Smooth Lighting=Maximum
might just be a bug with the new lighting engine.

I didnt find any bugs under " Signs Going Dark " so i posted this, sorry if theres another ticket similar to this.