That is a nice box. I would think the builder would want to know about the separation. The video on their site has him making detailed comments about their attention for quality. There are tons of comments by satisfied buyers, but it appears the vast majority are expressing delight at or shortly after unboxing.
I am also concerned about long-term stability of the board, which is why I asked for their response and am querying here. Their response was good. I'm just looking for user feedback to augment the buying process for a custom board.
Someone made me a nice board recently and it was their first. Looks good, great appearing wood, but squares are starting to show gaps of separation. And some of the unusual grains in the light colored squares are starting to splinter up. My guess is there was too much moisture content in the wood and I live in a dry environment. Eventually those mars will shred the felt pads under pieces. I don't want the acquisition of a nice board to become a long-term maintenance project!

https://www.threetreesworkshop.com/?category=Chess