I just experienced this detached wing thing too just now. I made this spaceplane here: http://imgur.com/a/Ha6Nu#0 The canards (allmoving style), a few of the control surfaces (b9 style) as well as the outermost wing tips on the rear set (sp+ style) are procedural wings. This thing flew into space, landed, and I exited back to the space centre (did not recover). I turned the game off for the night after the successful flight. Today, I loaded back into it to from the space centre main view (as opposed to the building with the scanning dishes, though not sure if it matters) and saw that the rear set of pwings were detached, but the other pwings that I used remained attached. The biggest difference that I could see between what detached and what didn't was struts. I had reinforced the connection between the pwings and regular wings of the set that bugged out, and didn't reinforce the connections of the ones that didn't bug out. I'll try another quick test shortly.