I guess its too early to know what happened. But as a comment, I did
personally witness an inflight structural failure in a wooden glider back
in the
UK. It turned out to be caused by an effect called a 'compression shake'
which is when a compression overload leaves the wood with a fine defect
that
is very weak in tension, so it can fail in tension at a later time, maybe
years
later. These shakes can apparently be detected by a careful visual
examination, by someone who knows what to look for, eg after an unusually
heavy landing or shock. Also there is a BGA note about glue joint
inspections
in gliders like K7s. I don't know if the FAA pass these on to US owners.

http://www.gliding.co.uk/bgainfo/tec...07-2004-issue-
3.pdf