Oh, they knew something. The sites that track betting percentages had ND receiving 75-80% of the bets, but the line was never adjusted upwards. In fact, there was actually reverse line movement in that sometimes the line was lowered to 19.5 / 20 / 20.5 to encourage more ND action.
For those interested in that kind of stuff, ESPN now has a page where you can track betting percentages:
http://www.espn.com/espn/chalk/liveOdds . Currently, re: Duke vs UVA, 58% of the bets are on Duke to cover the spread.
(Note, though, that percentage of bets made on a team does NOT have to equal percentage of money on a team. What the sportsbooks probably knew re: Duke at ND was that their sharp bettors were taking Duke, and the sharps make bigger bets than the average Joe Q. Public bettor. When the books know that the sharps are on one side [Duke] and the public is on the other side [ND], they are fine encouraging more public bets.)