I'm afraid there's no quest reward mechanic that I know of. I would have assumed HolyMan would have mentioned it to me when he was approving the adventure if there was, though we could both be unaware of it.
I really do feel bad that you guys are so close to your next level. If I'd done the XP calculations before I told you all it was over, I probably would have trumped up a verbal kerfuffle for you with Parsons or Caan, but I'd already sent you on your way before I realized it.
I feel especially bad since the reason I entertained the notion to try DMing was because my own LPF character had finished an adventure just shy of leveling. I realized having some DM credits available might help me do what IVV just did for Kazanto, compensating for such unfortunate timing.
If it's any consolation, over in Living 4th Edition, I had a character finish an adventure literally
9 XP short of gaining a level, so I definitely feel your pain.
It seems to me that most adventures, though, start with at least a few days of party introductioning / setup, so you might be able to petition your DM / adventure judge to allow for an early time xp award. It doesn't seem especially abusive a request to me.