Definitely heated too quickly. 1 degree Celsius per minute ramp up tops. Also, when we post cure multi piece molds free standing we fasten all the parts together to do so. Much less opportunity for warping. We do everything we can to hold the parts in place in the oven, even when doing “free standing” cures.

Yeh the sun is a really uncontrolled method of heating, and composites require really precise control. Not only is the ramp rate way too fast as KL mentioned, but there's also a good chance you got uneven areas of heat where some parts of the mould may have cast a shadow on themselves. If this happens, you have some parts of your mould getting up to 50°, and other parts still sitting at 20° or whatever. This is a disaster and will easily warp parts.

There is a good chance you can restore the mould however, but you will likely need your oven running well. If you bolt the parts together in proper position and then cure them above your previous temperature (I would do 70-80°), they will likely hold that position and fit back together well again.