I just bought a 50-500mm Bigma, and have noticed that there is the very, very slightest of movement in a twisting motion like youre taking off the lens(it actually less than 1/2 a millimeter) A couple other people with this lens states they have noticed the movement also. I have a 20D and a 24-70L that I have never noticed anything, probably because of the rubber seal at the mount. Is this something that is common on this lens or because it is so big that I'm not use to it.? Even a guy camera shop said that is what his does also....Am I being paranoid?

Thank you

with both my 70-200 and 400 there is a tiny amount of "give".