David pursued the matter and questioned whether or not the WW3 winds, which are also indicated as being at the surface, were suffering from the same problem. He contacted a member of the WW3 team and was able to verify that the winds used in the WW3 model are actualy at 10m, not the surface. It appears that NOAA plays a little loose with surface winds and 10m winds.
I contacted a member of the WW3 team as well, and they verified that the wind in the WW3 models are actually 10m winds.
I found two online sources which reference WW3 winds as being at 10m:
As of today, May 9th, 2017, the LuckGrib server cluster has been adjusted to move the wind data to the 10m level. This appears to be the correct thing to do.