The current PA13 has never voted in a Presidential election since the boundaries have been changed. The district changes took effect AFTER the 2000 race so these Bush/Gore numbers you are looking at are useless.
Not useless at all, the numbers cited are for the current district, they are the result of using the 2000 results for the precincts that are now in the current 13th. Thus the 55% to 43% reflects the voter leanings of the current district. Given that Gore won PA by 4%, the 13th is more Democratic than the state as a whole.