I believe the reason UND is ranked fairly high in the early season Sagarin rankings is that we beat Southern Utah on the road last year. That was our only FCS game. The only other thing I can think of is that another one of our opponents, Western Washington, defeated UC-Davis, and we beat Western Washington on the road. Based purely on strength of schedule so far this year, certainly we don't warrant such a high ranking.
A few other miscellaneous points about UND--we held a sizeable head-to-head advantage over NDSU and SDSU during the several years leading up to their move to dI (the last time we played was 2003). SDSU's head coach is 1-6 vs. UND. In our part of the country, where there are very few dI programs, we've historically been able to get a lot of talent that in other parts of the country would be at least FCS caliber, and probably FBS. That's part of the reason we were able to go into Northern Iowa two years ago and win.
Something else to keep in mind--even if you want to consider UND to be a dII team--which in essence we are until we've had a few more recruiting classes--there have been numerous examples in recent years of dII programs beating good FCS programs:
NDSU over Montana in 2003 (we beat NDSU that year)
North Alabama over Jacksonville St. in 2004 (we beat North Alabama that year)
Central Washington over Eastern Washington in 2006 (we beat CWU that year on the road)
UND over Northern Iowa in 2006
Western Washington over UC-Davis in 2007 (we beat WWU on the road last year)