What would you do?

I sold a surfboard on Craigslist to a dude two days ago.
He sent me this photo this morning, saying the board buckled on the first wave today.
The board had previously buckled, and I had it repaired by a professional shaper.
I’ve surfed the board a dozen times since the repair, with no issues.
I have the GPS Trace Tracker stats to verify my surf sessions on this board.
The dude who bought it from me is lighter than me by 30pounds.

What would you do?
What do you think is fair?