I remember about this time back in 2004, Specter was trailing 30% to 70%, yet they had already called the election for Specter. Republican votes will come in late in Pennsylvania, so don’t count Toomey out (although I must say I don’t have much faith in a state that would elect Bob Casey).
Same thing happened to Santorum against - yuck - Harris Wofford. They had Wofford as a Clinton shoe-in until Lancaster and other central precincts reported, putting Santorum over the top...
When I was an election judge in PA-10 it was 9:30 - 10:00 before I got the ballots to the county election office. Once there I had to stand in line to turn them in. It’s possible the more urban districts can get them in faster.