Hi, this mould is made from high temp epoxy and oven for 17 hours following the data sheet. 

I think I could of took more care in mould prep which didn't help. But it had about 8 coats of easy lease and struggled to out. Now the mould has carbon print through and cracked gel?

Carbon use xpreg xc110 oven cured following standard curing cycle.

Edit : carbon was in the mould over night before going in the oven as it was getting late and could fix leak in the bag.

This looks quite unusual for me. The only time epoxy gelcoat really cracks like that is if the mould flexed to much under excessive force. With such a small mould and >3000g/m^2 carbon reinforcement this seems unlikely.
There are two things I can say with certainty:
-There is something wrong with the gelcoat. Properly tempered there should not be any texture print. My best guess is the mixing ratio. To get this clear: I have never ever seen a bad charge of epoxy. problems were always caused by the user or a resin clogged scale.
-the sides of the mould really ask for trouble with mechanical lock.
IF the gelcoat was not mixed properly, the laminating resin might be mixed wrong too. This might make the mould flexible enough to crack the gelcoat.