What makes this particular signature more challenging for most authenticators is that it appears to be signed using a marker with a wedge (tanto-like) shaped tip.
Oddly enough, for me, the type of marker used locks it in as being unquestionably authentic, and that's because if you've ever watched Stan sign, you'd note that the changes in the angle of his writing implement would produce exactly what we see here where his track widens and narrows, based on how much of that tip touches the surface! This track perfectly reflects Stan's signing mechanism, IMO.
I appreciate the responses guys. You are correct they claim it was signed in 2014. The only thing I am concerned about is if they pull a fast one and the auto is preprinted. ( probably a paranoid though)
Look at the feathering of the ink at the periphery of the written lines. It's what's expected, for the ink of the sharpie to soak outward into the paper immediately bordering the tracks.