Right now the author just "quickfixed" it to force the Blizzard_AuctionUI to be loaded on startup (.toc depency) ... I want my AucionHouse loaded on demand, so I tried to fix it ... and it works for me
I added the following line to the AHFav:Initialize() function
-- reparent / position the AHFavs frame
AHFavs:SetPoint("TOPLEFT", "AuctionFrameBrowse", "TOPLEFT", 195, -45)
and finally, removed Blizzard_AuctionUI from the .toc of course.
Works nice for me... so if anyone wants it, here is the url