I've just taken delivery of the Panasonic 14-140 f3.5-5.6 lens and I'm not sure if there's something wrong with it. It's making a hissing sound (which goes away whilst zooming) and I was wondering if anybody else has experienced this. I have it on my OMD, IBIS on, lens OIS set to OFF. Is this a "feature" of this particular lens? I have a number of Panasonic lenses and none of them make any noises. I'm finding it quite irritating.