If this "uvula thing" never happened before on your other 25+ lifetime dives, you should be asking yourself: "What was different about this last dive?"
If the cause was, in fact, breathing dry tank air, why didn't it occur on any of your other dives?
Dry mouth is one of the most common anticholinergic side effects of antihistamines.
To stave off seasickness, lots of divers take Bonine (meclizine) or Dramamine (dimenhydrinate), both of which are antihistamines.
I'll reiterate one of my previous questions. Were you taking any medications (e.g., for seasickness, for allergies) at the time?
The sucking-on-hard-candy trick is a good one for dry mouth, particularly when you are topside. Exercise care if you decide to do this to address your dry mouth issues while diving. Something to be aware of is that it is possible for the piece of hard candy to turn into an airway obstruction. There's a very low chance of this happening, but you would be SOL if it occurred while you were at depth. FWIW, I'm not aware of any scuba accidents that have involved a diver choking on a piece of candy.