Thanks for the reply,
We currently do not warm the molds, and havent had issues (yet) as described in the link you added.
If the mold is filled in from below it would then contain a larger mass - wouldnt it then cool faster? I can only imagine a greater dispersion of heat from the chocolate into the mold itself. Its worth noting I am not knowledgeable in this by any means, and am just creating my own theories.