`frame-background-mode' incorrect with initial frame

I set my default face to black from within custom, but XEmacs doesn't realize that my frame-background-mode is dark until it opens a second frame. Thus, for the first frame, a lot of my text is hard to read because it picks the colors for a light background. I've noticed this problem with multiple versions of XEmacs, and on multiple computers (even with my friends' own setups), so I know that it's not isolated to a quirk on my machine. I currently get around the problem every time I start a new XEmacs process by killing the initial frames, and opening up new ones in their places before doing any work. Is anybody aware of this already? Is it a problem that won't go away anytime soon? I investigated it once for a while, and it seemed to have something to do with the timing of the loading of custom's face settings, and some specifier cache or something... I don't remember the details.