I can't address the "silver" version but I do have the black 1.4/50 ASPH. I noticed a slight stiffness in the focus only in one area of the throw. I posted and had several enlightening discussions at the time.
I would have described the feeling not as sticky but just slightly stiff in one area of focus but nothing that I would consider as a problem. I got similar confirmations and most seem to agree that it was noticeable but not a significant issue (not to put words in folks but just summarizing).
It seems there was some consensus that it may have been related to the ASPH element in the 50 focal length or some other slight tolerance issue but at the time I didn't see any correlation to the barrel material, it just seemed random.
Regardless of what it was, it has just about disappeared with regular use so either the movement has loosened up or something else has changed but I can tell you that I think the lens is magnificent and I now have zero complaints (and excuses
) and the focus is much smoother.
FWIW, my 1.4/35 ASPH was a bit more used when I got it and it had no hint of stiffness.