focus ring looseness in Canon 100f2.8 Macro

I just got the (non IS) Canon 100 mm macro, and noticed a slight movement in the focus ring when I try to move it. This happens when the AF/MF switch is in either position.
Is this small amount of "slop" normal? I am asking, since an inquiry was posted in the regular lens section of the forum. An answer to this didn't appear, and I thought that there would be lots of Canon macro users here.
The focus ring moves about 1/2 or 1 mm before engaging.
The lens usually hits focus at normal or close ranges, but I wondered about the motion.
Is this normal for the lens?

i have this lens, mine is quite loose now! over used in manual focus
think it was a little loose when originally bought . doesnt affect how it handles.
dont worry

phil