James,
This came up last year, about the time I bought my 80-200 and F5. Mine
is exactly the same. However, I think, on close inspection, that the
movement is in the outer casing of the lens, rather than the mount. I
reckon that the movement is not important and probably has something
to do with the way the lens was assembled-dropping the casing over the
internal gubbins. Certainly, mine has performed perfectly for the last
year.
Stewart.
