I have noticed something very weird about my neighbor's roof: there is
a large rectangular area on her roof that is wet most of the time. I
took pictures of it and showed it to her, but neither me nor her can
figure out what could be causing it. If anyone here knows anything
about roofing, please take a look at these pictures and see if you can
figure out what the problem might be.

The neighbor's bathroom is pretty much right there were this wet spot
is. Her ceiling in this bathroom is vaulted. We were thinking it could
be condensation, but if it in fact is, will this constant moisture not
damage the roof over time?

Pictures numer 1 and 2 were taken on a cold morning at 7:30, the area
that is wet shows frost on the roof, while the rest of the roof is
pretty much frost-free. The other pictures were taken two days before
the frost ones, also at 7:30 in the morning, but it wasn't as cold that
night so the roof is only wet in this one spot. The rest of the roof is
dry. Also, the dark lines that you can see on the roof are always
there, even when the spot on the roof is not wet.

This is a house that was built 6 years ago. And, in case it matters, we
are in North Alabama.

http://i133.photobucket.com/albums/q...3/HPIM1350.jpg
http://i133.photobucket.com/albums/q...3/HPIM1349.jpg
http://i133.photobucket.com/albums/q...3/HPIM1347.jpg
http://i133.photobucket.com/albums/q...3/HPIM1346.jpg
http://i133.photobucket.com/albums/q...3/HPIM1345.jpg
http://i133.photobucket.com/albums/q...3/HPIM1344.jpg
http://i133.photobucket.com/albums/q...3/HPIM1342.jpg

Any input would be appreciated!

Angie