Thanks @mimmy. To be honest, i was never into making chocolate, because there is a tempering process you need to go through to make sure chocolate doesn't look white when its drying. Very complicated to me :-)
The mould I used is made of silicone, not plastic. And as far as i know its safe. I mean, nothing in life is 100% safe :-). But it also says it is meant for fondant,clay, not really for chocolate. As i said in my post, the first round went very well. The second less good. If your chocolate tastes good, then it doesnt matter how it looks like :-).