My best guess is that no one tried to steal the election, but we don't know that. That Romney was shut out 19,600 to 0 in 59 Philadelphia precincts in the previous presidential election is most likely just that: No one voted for him. Still, these things leave room to wonder if the system is being hijacked. This makes two presidential elections in a row, then, that Pennsylvania has raised our eyebrows.
We are told, if the hack is done right, the perpetrator can get away without leaving signs. So, we should not be too lackadaisical just because there is no evidence. Rather than reject recounts, they should become standard practice. If you have a chance of fraud, you guard against it. You place safeguards in your system. Companies audit their books all the time. Why would we not do the same with our elections?