The problem with early exit polls is, among other things, they poll people who vote early more heavily, while working people, who may favor Hillary, vote later. And they have typically tilted to Obama during this primary season.
But there's still a few minutes till the Pennsylvania polls close, so here's some comparisons of a few exit poll numbers in Pa. and Ohio, where Clinton won by 10:
CNN shows Clinton winning 55 percent among white men. In Ohio, she won that group 58-39.
CNN shows Clinton winning 61 percent of voters over 65. In Ohio, she won that group 72-26.
ABC News has just under half of Pennsylvania voters with a college degree. That number was 38 percent in Ohio.
So, the signs are either that Obama will do better in Pennsylvania, or early exit polls continue to skew toward Obama, as they have in past primaries...