Recently, David Burch alerted me that the NDFD wind level appeared to be incorrect, and that it should be at the 10m level, not the surface. The NDFD winds were recently adjusted to account for this.
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:
The wind level has been adjusted
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.