agreed, buy the house if all esle is good

mold will tend to grow on the inside of a roof that faces north and
does not get sun in the winter

the south facing side gets the sun and dries out and all the moisture
condenses on the north facing side

with the added attic vents, it might not re-occur

just check it every year and apply bleach as required or add more
ventillation

i suggest a vent on two sides so that you get air flow due to the
prevailing wind

Mark