Yeah, figured it was something to do with the double layed board and the different mass of the two layers expanding / contracting with temperature at different rates. That said, I've never seen it to this extent before and never had any problems with my Scythe boards. I live in Ireland too, which has a super mild climate. No weather extremes here!
Anyway, they're all currently being crushed under piles of books or other game boxes, so hopefully they'll be all sorted in a couple of days!
We've seen this behavior with about a third of the boards, based on rough estimates on the comments.
We're talking with Panda Games about this. They had let us know that this was one of the most elaborate double layer boards they've ever made, and that maybe they need to be held longer in the drying room before gluing.
I have my own boards under a few books right now as well. It seems to be working well!