There could be a problem there when the heat expands but i don't think a 24/7 run over just 3 days would cause that to happen it looks like a manufacturing fault.

Dont forget some systems do go beyond recommend temps. If this is a one off fault your in the right place to find out, as im sure there will be more posts appearing if its common problem.

Your the first from what i can see. But give it time.

Its a very rare event to see a Res fracture at the points of contact but not beyond the realms of possibility.