I've traveled without problems on Travelocity-purchased AA tickets, as well once on one of those last-minute package deals. However, I did have a problem once at OAK when the agent was unable to pull up my ticket for the old OAK-DFW redeye, connecting to an AA international flight. My name, the pax list for the flight, the booking code I had, nada. I had brought the Travelocity receipt, but apparently it lacked the ticket number, or there was some similar problem.
She tried for the better part of half an hour (FYI, there were other TAs there who were able to help the other pax). At that point, she told me I would have to contact Travelocity. Just as I was on hold with Travelocity (and it was clear I was going to miss the flight because of the Travelocity hold times), the supervising TA came over and did a search based on my credit card number. The ticket immediately came up, and the supervisor seemed to think this was a very common solution to that kind of problem.
Long story short, this was a solution to the "missing ticket" problem I hadn't known about. It made for an exciting wait at the ticket counter, that's for sure.
-Hayden