I am over a hundred completed resin kits from all manufacturers and I have never had the problem. I also, always internally brace my resin models.
Paul leads a charmed life, indeed, especially if he is referring only to one piece resin house cars.
Out of the last five one-piece house car kits that I have purchased, two have been seriously warped, one yet to be tackled, and one to the extent that it had to be internally braced with a whole forest of styrene shapes- the process of which exhausted my supply of small clamps (and it still has a warp- hopefully disguised by the weathering and details).
Routinely internally bracing resin house cars is probably a very good idea.
