IMO it is a warranty issue IF the front seam doesn’t have any voids in the sealant.
So how did you inspect the seams/seals? Not trying to pick on you, but if there is voids in the sealant, that IS a maintance issue and any RV maker will only cover the first 90 days of ownership. Sucks but that’s the sad truth.
I would be taking LOTS of pictures, documenting the front seam and sealant.
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2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.
Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.