After seeing exactly what your talking about with the window, it is very likely that it has run down inside the wall over time. I'm guessing you haven't seen any signs of delamination on the outer skin, on the inner paneling, or damp spots inside? Definitely needs to be fixed or replaced asap, as in the window. Even if its not that, the gasket coming off will cause problems.
John and Rebecca Dickson
Emma-7 / Little John-5 / Iva-1
Full Timing Again, Rev B
2013 Ford F-350 Lariat CC LB PSD
2015 SOB TT - With OC's Awning Poles (#8)
At least in Heaven, RVs will be perfect, and I won't have to keep fixing them.