Hi Woody, good to see you back again, hope your doing well... of course your welcome here!
In regards to your issue, it is a problem commonly known as lens creep and it is known to affect various lenses. Not being a Nikon man I don't have any info as to whether the 18-200 VR is a known sufferer but I'm sure the Nikon brigade will be along soon to give you some more info.
*Edit* - OP beat me to the post button!