As mentioned previously I took the bike to DC via Amtrak over the past week and put another 50 or so miles on it with a few folds mixed in -- no problems whatsoever.
Jur: thanks for the duct-tape trick. I did add a bit to the area that received the most initial damage. It didn't eliminate the few creaks and squeaks I'm getting from the hinge, but I like having it there nonetheless. (And, they're really not that bad -- I suspect they've been there all along, and I'm only noticing them now due to my worries about the health of the hinge.)
Still no word from Dahon after two emails over two weeks, and the shop from which I purchased the bike isn't doing anything to help. According to them, I've got a better chance to hear back from Dahon about getting such a part than they do. Despite my frustration I won't divulge the name of that shop but, clearly, there's a reason for why their price was so much lower than elsewhere.
Finally, I suspect this thread has surpassed its interest-lifespan
I won't resurrect it again unless I do ultimately hear back from Dahon, but I wanted to give one final thanks for all of the help I got. This turned out to not be such a big deal, but that was not initially clear to me, and with no local dealers, a complete lack of help from the shop from which I bought the bike, and total silence from Dahon, I really would have felt out in the cold were it not for the community support of this forum -- thanks!