Looks like Obama has reclaimed his commanding lead among college grads tonight. If the exit polls are to be believed, he's won them by 14 points in North Carolina and 12 in Indiana. Two quick thoughts about why that was: 1.) There was never quite the hemorrhaging we thought there--Pennsylvania's result was really an anomaly (a function of Ed Rendell and a general Rust-Belt conservatism). 2.) This group responded especially well to Obama's stance on the gas tax.
I'd guess it was some combination of the two.