Here it says:
http://art-atel.com/htm/program/blender/help/htm/pyscripts/eip/vrml/exporting_web3d_vrml.htm#4

Headlight

Headlight is a light that always follows the viewer and an attribute of the node NavigationInfo. If there are no lights at the Blender scene it will be turned on, if a light is present it will be turned off.

After the export, the file has:
<NavigationInfo headlight="false"

I am using latest stable blender release (2.67a) for windows 64bit

I have deleted all lamps from the scene in blender and there is no light or lamp in the x3d file.