Can't see why that would not be under the 2-year Jayco warranty, unless they could prove owner misuse, which would be very difficult. Looks to me like the dealer just doesn't want to bother. As stated above, I would call Jayco direct and let them tell you why is isn't warrantied, if that is truly the case.
2003 Ford F-350 V-10 Crew Cab 4WD Long Bed
2004 Jayco Designer Medallion 29 RLTS 5th wheel
Bill, Gayle, and Mindi (dachshund)
Retired at last !
Nothing is foolproof to a sufficiently talented fool.