delaminated ceiling

Is it just the thin vinyl covering, like a wallpaper or is it the vinyl and backing material such as a luan? If it's just the thin part like a wallpaper and you're sure the leak issue is solved, I'd do the same as if I had a bubble in some wallpaper. A sharp single edge blade, make an X so that you can fold the sections back that aren't adhered. Use a good wallpaper adhesive and apply to the vinyl and use one of those plastic smoothing tools - maybe 4" or so and gently smooth out the bubbles. Take a slightly damp cloth and wipe any adhesive that squeezes out and let it dry. You may still see the cuts from the razor blade, but the adhesive should eliminate the bubble. If it's more than just what I've described, I'd leave well enough alone. If it's into the backing/luan/whatever I wouldn't mess with it.

This is why everyone should give those 4 bolts on the A/C a
snugging up every spring!

We too have a 2007 Jayco 23B. Here's a couple of posts I put in after dealing with my roof issues:
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/23754930.cfm
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/23922553.cfm
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/24082462/gotomsg/24084836.cfm#24084836

X2, leave it alone.

If it is not soft I would leave it alone. You may create more problems by trying to make a correction. Jaco has a good reputation I would contact them to see if a fix is possible.