I used Titebond II Premium. It's the only glue I've used since I started building.I would be interested to know what type of glue did you use for the wales?
I think the problem is the the type of wood and expansion. The planking underneath is Nussbaum (Walnut??). Since both the Port and Starboard pieces have done the same thing I suspect there never was a good bond. I think a replacement is the best bet, since there appears to be a slight bubble effects I place the clamps.
Hah, now that I typed that I don't know if it makes any sense.
The bubble sort of moves as I clamp, I think that's because neither the bow or stern sections of the Wales have come unglued.
Jan