In the very same areas, I sometimes get the Trackless Step bonus to hide/MS and sometimes don't with my ranger character. This also seems to apply to the movement speed bonus in wilderness regions.
It's as if the bonuses sometimes stay on after entering a non-wilderness region from a wilderness one.
The character is a goblin (informal), dunno if the subrace skin makes any potential difference.
I find this sometimes happen to me too, but I think I heard it's just something that 'happens'.
It's what Inq said.