I agree with your point (it's always nice to have unexplained things at the edge of the map), but it has actually been expained before(albeit in a humourous & possibly-just-to-get-a-rise way) in the q continuum trilogy.
Heh, I didn't know that. Somehow, given what I know about the Q books, that doesn't bother me.
Also, James Swallow
could've decided to ignore that/read it as "Q was kidding" and given a straight explanation.
Still, that's yet another reason why I need to get the Q Continuum trilogy!