Under venting can cause condensation and roof leaks cause conditons for
mold. Leaks have happened in the houses history it is normal so can old
mold be normal. A moisture meter can pinpoint wetness, and leaks
present. Condensation occurs on a cold sunny day or water after a rain
can be found with a moisture meter. If vents were added it should be an
old issue which simply spraying bleach will fix. But of course now you
will have the fearfull recomending testing and special overpriced
removal services. If you can determine it isn`t growing then don`t
worry, mold is everywere, everytime you come home its on your shoes.
Bleach does wonders and only 89c a gallon.