Hey guys,
I'm kind of very fresh to resin casting, doing some personal mini projects only.
The story is: About a month ago I made 2 silicone moulds out of my clay sculptures using CS25 Condensation Cure Silicone Rubber.
It served me great, made about 40 casts (using Xencast P2 Fast Cast Polyurethane Casting Resin) from both of these. Yesterday I decided I need to cast a few more aaaand
One of these two turned out normally, just mixed the resin in equal parts, poured it in and in half an hour I had a ready sculpture to take out.
But the second one... the silicon basically got stuck to the resin? I couldnt take it out, mostly had to cut it out to see what has happened. 
On the first picture it's the silicon stretching, not the cast that has poured into the walls of the mold. On the second photo, once I got it out, its all covered in little silicon bits... 
I'd like to know what have I done wrong? Any ideas? both moulds were identical and made together, same with the resin I used - poured it from the same cup... and one is fine, the other got ruined. Wish I could prevent that in the future!

Thanks!
maggie