That classic prose came with the lens. Reading further, this time in the camera manual, it says that when using a lens weighing more than one kg, don't carry the kit around just by the strap. Taken with other warnings, it seems Panasonic is afraid the lens mount on the G1 isn't strong enough to support a 1.5 kg lens in all cases unless the lens is supported by something other than the mount. Since the GH1 body is thicker than the G1's, I wonder if they've beefed up the mount.