If you show up with the ticket without being previously reissued or authorized, you should expect both a reissue and an aneurism on the part of the agent.

If youre doing the JFK thing because of wanting to go on the 762, you might want to check out a thread in the AA forum stating that the 762 is back on the schedule of the LAX-BOS route. I didn't look closely at it but what I saw it appears that it's being sold as three class.