Actually, for something like this I would have bent my rule even if it didn't come from Universal. I would not buy from Ticketmaster, though, as two PPs can attest to. They were given bad information by Ticketmaster and sold passes that did expire and were not upgradable. That wasn't the fault of Universal, even though I have been told by at least one person that this happened to that they after speaking to a manager at guest services they were ultimately allowed to upgrade to a preferred AP. I can't attest to the truth of that, but the person that told me has no reason to lie.
The long and short of it is, if you have tickets with no expiration date, they are going to honor them.