[Stripit]

Yep lets all make assumptions, I would go up with a soft brush, some diluted bleach or a mold killing soultion and try a small area. Then I would know if it is mold, or totally worn out TPO roofing material. I used to clean my 2004 36 TK3 with a low pressure pressure washer, Murphy's Oil soap and a softer brissel brush every year. Depending on the climate we were in and the amount of wet weather,when I had small mold spots and they washed off when I cleaned the roof. I sold my trailer in 2015 and the roof was white and clean when I sold it with no signs of failure.