That is because the storyline of HotU actually is the following the character from the SoU expansion, and not the original NwN.
Of course, it makes little difference which character you use, because all NPC/Storyline behavior is scripted into the game, and not dynamic. So while the NwN henchmen dosen't recognize you, the SoU one will (regardless of playing SoU I think). Also you should have/find a book early on, that descripes your adventure in SoU as descriped by the books author (the SoU henchmen in HotU).
Hope this clears up the confusion
