That looks like one of those under a tree stains, but I don't know if yours is under a tree at that area. Your roof should be a Dicor Diflex II TPO roof. I only mention that as there was nothing in our stack of papers on what ours had, so a call with vin verified that they were using this particular roof now. Used to be the Alpha.
John and Rebecca Dickson
Emma-8 / Little John-5 / Iva-1+
2013 Ford F-350 Lariat FX4, CC LB PSD, DRW
2015 Jayco Jay Flight 28BHBE (#8)