If it didn't creep, we'd probably be talking about how stiff the zoom ring is.
I've used my neighbor's and it creeps. It's really not that bad. The Tamron 28-75 has the same issue and so did the Sigma 50-500 that I had at one time..(and you could trip over that lens) LOL. It's a small price to pay for the convenience of the 18-200 zoom. It's not all THAT bad.
Julio