Canon 28-135 USM IS Ultrasonic AF ZOOM Lens Shake

Hi,

just a question, I have just bought on ebay a Canon 28-135 USM IS
Ultrasonic AF ZOOM Lens. It looks like working well, but I noticed that
the front lens support (the one on where the front lens is attached) is
moving a little bit, as is not really fixed on the rest of the body of
the whole lens.

Just to know if it is normal of this kind of Canon USM lens or I have
to return back the item to my seller... sounds a little bit strange to
me that part of the body is not so fixed to the rest of the lens.

Thanks in advance for your support.

Stefano