The day we took posession of our 2010 TT, the owner of our dealership had specifically told me that two year warranty will not transfer to a second owner. This was Sept '09. I'm not sure if that would be when they changed the "rule" on that, but I do know at one point the warranty would transfer. If you are buying a "new" Jayco still under original owner warranty, do your own "pdi" and ask that the current owner take it down to the dealer for warranty work you notice. It wouldn't hurt to contact Jayco directly to verify your questions.
Another thing to consider, give Jayco the VIN# of the Jayco you are considering purchasing and see if they will give you the name of the original owner (which may be the only name in their warranty records) and it doesn't match the name of the guy/gal selling it now. That could indicate the owner themselves could be the second owners already and are having some kind of troubles with the tt. Probably not, just a story a fellow camper shared with us once.